Linux Command Introduce

Name: Cat

Use permission: All users

How to use: cat [-abeensttuv] [--help] [--Version] FileName

Description: Connect the file to the basic output (screen or plus> filename to another)

parameter:

-n or --Number is numbered by 1st of all outputs

-b or --Number-nonblank and -n, but not numbered for blank lines

-S or - SQUEEZE-Blank When there is a blank line with two consecutive lines, it is changed to a row of blank lines.

-v or --show-nonprinting

example:

CAT -N TEXTFILE1> TextFile2 Enter the textFile2 file after adding the file content of TextFile1

CAT -B textFile1 TextFile2 >> TextFile3 adds the contents of TextFile1 and TextFile2 to TEXTFILE3

Name: CD

Use permission: All users

How to use: CD [DIRNAME]

Description: Transform work catalog to Dirname. The DiRName representation can be an absolute path or relative path. If the directory name is omitted, transform to the user's Home Directory (that is, the directory where Login is located).

In addition, "~" is also expressed as HOME DIRECTORY, "." Means the current directory, ".." indicates the current directory of the current directory location.

Example: Jump to / usr / bin /:

CD / usr / bin

Jump to your own home Directory:

CD ~

Jump to the upper two layers of the current directory:

Cd ../ ..

Directive Name: Chmod

Use permission: All users

How to use: chmod [-cfvr] [--help] [--version] mode file ...

Description: Linux / UNIX file access rights are divided into three levels: file owners, groups, others. Using CHMOD how to control the file is accessed by others.

Tie count:

Mode: Permissions set strings, formats are as follows: [Ugoa ...] [ - =] [RWXX] ...] [, ...], where u indicates the owner of the file, G represents the file The owner belongs to the same group (Group), o other people, a means that these are all.

Represents increased permissions, indicates cancellation, = indicates unique setting permissions.

R indicates that readable, W represents written, x represents executable, X represents only when the file is a subdirectory or the file has been set to be executed.

-c: If this file authority does have changed, it will display its change action.

-f: If this file is not changed, do not display an error message.

-v: Details showing permission changes

-R: The same permissions change in the current directory with the subdirectory (ie, changed by one by one)

--help: Display auxiliary instructions

--Version: Display version

Example: Set the file file1.txt to everyone can read:

CHMOD UGO R File1.txt

Setting the file file1.txt can be read:

CHMOD A R File1.txt

Set the file file1.txt and file2.txt to this file owner, which is written with its own same group, but other people cannot be written:

CHMOD UG W, O-W File1.txt File2.txt

Set the ex1.py to only the file owner can perform:

CHMOD u x ex1.py

Set all the files and subdirectories in the current directory to anyone read:

CHMOD -R A R *

In addition, CHMOD can also use numbers to express permissions such as CHMOD 777 file.

Grammatical: chmod abc file

Where A, B, C are each number, which represents USER, Group, and Other permissions.

R = 4, w = 2, x = 1

To RWX attribute 4 2 1 = 7;

To RW-attribute 4 2 = 6;

To R-X attribute 4 1 = 7.

example:

CHMOD a = rwx file

with

CHMOD 777 File

Effect

CHMOD UG = RWX, o = X File

with

CHMOD 771 FILE

Effect

If you use CHMOD 4755 FileName, this program has root permissions

Directive Name: Chown

Use permission: root

How to use: chmod [-cfhvr] [--help] [--version] user [: group] file ...

Description: Linux / UNIX is multi-person multi-work industry, all of which have owners. Use Chown to change the owners of the file. In general, this instruction only is used by the system administrator (root), and the general user has no permissions to change someone else's file owner, and there is no permission to change the owner of its own files to others. Only the system administrator (root) has such permissions.

Tie count:

User: New Archive owner's user IDGroup: New Archive owner's User Group (Group) -c: If the file owner does have changed, the change action is displayed - F: If the owner cannot Do not display the error message - H: only for links (LINK), not the LINK, true pointing file -V: Display owner change - R: All files and subdirectories in current directory Perform the same owner change (ie, changed one by one by way) - Help: Display Auxiliary Description --Version: Display version

Example:

Set the owner of the file file1.txt to the User Group User Jessie:

Chown Jessie: Users file1.txt

Set all the files in the current directory with the owner of the subdirectories Lamport:

CHMOD -R LAMPORT: USERS *

Name: CP

Use permission: All users

Use mode:

CP [options] Source Dest

CP [Options] Source ... Directory

Description: Copy a file to another, or copy several files to another directory.

Put on

-a will copy the file status, permissions and other materials as much as possible.

-r If the Source contains a directory name, the files in the directory are also copied to the destination.

-f If the destination already has the same file, it is deleted before the replication is removed.

example:

Copy the file aaa (already existing) and name BBB:

CP AAA BBB

Copy all C language to the finished subdirectory:

cp * .c finished

Name: CUT

Use permission: All users

Usage: cut-cnum1-num2 filename

Description: Shows the text that counts Num1 to Num2 from the beginning.

example:

Shell >> Cat Example

TEST2

this is test1

Shell >> Cut -c0-6 example ## print starts the first 6 words

Test2this I

Name: find

Usage: find

Instructions for use :

List of files that comply with Expression in the archive system. You can refer to a combination of different information such as the name, category, time, size, permissions, etc., only fully matched.

Find determines the Path and Expression on the following rules, first on the command - (), the previous part is PATH, after which is Expression. If PATH is a empty string, use the current path, if expression is the empty string, use -print as the preset expression 

There are more than two or thirty options that can be used in Expression, which only introduces the most commonly used part.

-mount, -xdev: Only check and specify files under the same archive system, avoid listing files in other archives systems.

-AMIN N: Readed in the past N minutes

-anewer file: Archives read later than files File

-Atime N: Files read in N days in the past

-cmin N: Modified in the past N minutes

-cnewer file: file updated than file file

-ctime N: Archives in the past N days

-empty: Empty Archive - GID N or -Group Name: GID is n or group name is Name

-ipath p: -path p: The path name is compliant with the file, IPath will ignore the case

-Name Name, -iname name: The file name is compliant with the file. INAME will ignore cases

-Size N: The file size is N unit, b represents the block of the 512-bit group, c represents the number of words, and k indicates that kilo Bytes, W is two bit yuan groups. -type C: The file type is C file.

D: Directory

C: Dictionary device file

B: Block device file

P: Total list

F: general file

l: Symbol connection

S: socket

-PID N: Process ID is the file

You can use () to separate the arithmetic, and use the following operations.

EXP1 -AND EXP2

! expr

-Not EXPR

EXP1 -OR EXP2

EXP1, EXP2

example:

List of all extended files in the current directory and its subdirectory is C.

# Find. -name "* .c"

List all the general files in their underlying directory

# Find. -ftype f

List all files updated in the current directory and its subdirectory

# Find. -ctime -20

Name: Less

Use permission: All users

Use mode:

Less [option] FileName

Description:

The role of Less is very similar to more, can be used to browse the content of the text file, the different is that the LESS allows the user to go back

To browse some parties that have been seen, because LES is not entered into the entire file at the beginning, it will be fast than the general instrument editor (such as vi) when encountering a large file.

example:

Directive Name: LN

Use permission: All users

How to use: ln [options] Source Dist, where Option is:

[-BDFINSVF] [-S backup-suffix] [-V {numbered, existing, simple}]

[--help] [--version] [-]

Description: In the Linux / UNIX file system, there is a so-called link, we can treat it as an alias of the file, and the link can be divided into two: hard links and soft links, Hard connection means that a file can have multiple names, while the soft connection is to generate a special file, which is the location of another file. Hard links are in the same archive system, while soft links can span different archive systems. The LN Source Dist is a link (dist) to SOURCE, as for the use of the hard link or soft link, is determined by the parameter.

Whether it is a hard link or soft link, it will not copy a copy of the original file, and will only take a very small amount of disk space.

-f: The file will first delete the file with the DIST: Allow the system administrator hard link to your directory -i: When deleting the file with the DIST, I'm inquiry -N: On When the soft link, the Dist is treated as a general file-S: Symbolic link -V: The file name is displayed before the connection - B: Backup of files that will overwrite or deleted during the link - S Suffix: Plus backup files with SUFFIX's word-V Method: Specify the way backup - HELP: Display auxiliary instructions --Version: Display version

Example:

Generate a Symbolic Link: ZZ with the file yy

Ln -s yy zz

Generate a Hard Link: ZZ with the file yy

ln yy xx

Name: Locate Usage Permissions: All users

How to use: Locate [-q] [-d] [--Database =]

Locate [-r] [--Regexp =]

Locate [-qv] [-o] [--output =]

Locate [-e] [-f] <[- l] [-c]

<[- u] [-u]>

Locate [-VH] [--Version] [--help]

Description:

Locate allows users to quickly search for the specified file in the archive system. Its method is to build a database including all file names and paths in the system, and then only query this database when looking for, without having to go deep into the archive system.

In a general distribution, the establishment of the database is placed automatically in the contab. General users use as long as used

# locate your_file_name

The model is OK. parameter:

-u

-U

Establish a database, -U will start by the root directory, and -U can specify the starting location.

-e

will

Exclude outside the range of findings.

-L

If it is 1. Start safe mode. In safe mode, the user will not see the file that is not available. This will slow down because Locate must obtain the permission information of the file in the actual archive system.

-f

Except for a specific archive system, for example, we have not reached the tool in the Proc archive system in the database.

-Q

Quiet mode does not display any error messages.

NN

At most displayed output.

-r

Use the regular operation to do the conditions for finding.

-o

Specifies the name of the information inventory.

-d

Specify the path to the database

-H

Display auxiliary message

-V

Show more messages

-V

Display program version message example:

LOCATE chDRV: Looking for all files called ChDRV

LOCATE-N 100 A.out: Look for all files called A.out, but only 100

Locate -u: Establish a database

Name: LS

Use permission: All users

How to use: ls [-ALRTAFR] [name ...]

Description: Displays the contents of the specified working directory (list the files and subdirectories included in the current working directory). -a Displays all files and directories (LS demonstrates the file name or directory name "." will not be listed as hidden files.

-L In addition to the file name, the file type, authority, owner, and file size is also detailed.

-r Displays the file in the opposite order (originally in the order of English)

-t lists the priorities of the file according to the establishment time

-A, but not listed "." (Current directory) and ".." (parent directory)

-F adds a symbol after listed by the file name; for example, the executable is added "*", the directory is added "/"

-R If there is a file in the directory, the following files are also listed.

example:

List all the names in the current working directory, the beginning of the beginning, and the more advances are reached:

Ls -ltr S *

List all directories and file details below / bin directory:

Ls -lr / bin

List all files and directories under the current working directory; directory is added later, "/", can perform files after adding "*":

LS -AF

Name: more

Use permission: All users

How to use: more [-dlfpcsu] [-num] [ / pattern] [ linenum] [filenames ..]

Description: Similar to CAT, it will make the user's page-by-page reading at a page, and the most basic instruction is displayed in the next page of the blank key (Space). Press the B button to go back (Back) One page shows, and also has the function of searching strings (similar to VI), in use, press H.

Parameters: -num number displayed

-d Tips, display [Press Space to Continue, Q to Quit.] below the screen, if the user presses the wrong button, [Press H for instructions.] is displayed instead of beep.

-l cancels the function of meeting special character ^ l (paper feed characters)

When calculating the number of lines, the number of rows after the actual line (some single lines will be expanded to two or more lines)

-p does not display each page in a rolling manner, but first cleared the screen and then display the content.

-C is similar to -p, different is to display content and then clear other old materials.

-S When you encounter a blank line with two consecutive lines, it is changed to the blank line of a line.

-u does not display the lower quotation marks (different depending on the termage specified by the environment variable TERM)

/ Search the string (Pattern) before each file is displayed, then start displaying from the string

NUM starts from the Normal line

Filenames can display the file file, can be multiple numbers

example:

More -s testfile Displays the file content of TestFile, if there is a row, the blank line is displayed in a row of blank lines.

More 20 Testfile starts the contents of Testfile from the 20th line.

Name: MV

Use permission: All users

Use mode:

MV [Options] Source Dest

MV [Options] Source ... Directory

Description: Move a file to another, or move several files to another.

Parameters: -i If the destination already has the same name file, first ask if the old file is overwritten. example:

Rename the file AAA as BBB:

MV AAA BBB

Move all C language programs to the finished subdirectory:

mv -i * .c

Name: RM

Use permission: All users

How to use: rm [options] name ...

Description: Delete files and directories.

Put on

-i before the deletion, please ask for confirmation one by one.

-f even if the original file property is set to read, it is also directly deleted without one by one.

-r Detects the directory and below.

example:

Delete all C language program files; ask one by one before deleting confirmation:

Rm -i * .c

Delete all files in the Finished subdirectory and subdirectory:

RM -R finished

Name: RMDir

Use permissions: All users with appropriate permissions in current directory

How to use: rmdir [-p] DIRNAME

Description: Delete empty directories.

Parameters: -P is that when the subdirector is deleted, it will also be deleted by the way.

example:

Delete the subdirectory named AAA in the working directory:

RMDir AAA

In the BBB directory in the working directory, delete the subdirectory called TEST. If the Test is deleted, the BBB directory is empty, then BBB is also deleted.

RMDIR -P BBB / TEST

Name: split

Use permission: All users

How to use: split [option] [INPUT [Prefix]

Description:

Split a file into several files. From the INPUT division output into a fixed-size file, its file name is prefixaa, prefixab ...; prefix preset value `x. If there is no input file or `-, you will be read from the standard input.

匡 兜 

-b, --Bytes = Size

The size value is the size of each output file, and the unit is BYTE.

-C, --Line-bytes = size

In each output, the maximum number of BYTEs in a single line.

-L, --Lines = Number

The Number value is the size of the column size of each output.

-Number

The same as -l Number.

--Verbose

Print the detection information to standard error output before each output file is opened.

--help

Display auxiliary information and then leave.

--Version

Listed by this information and then leave.

Size can join the unit: b represents 512, K represents 1k, M represents 1 meg.

example:

Postgressql Large Data Library Backup and Recycling:

Because Postgres allows the form to have a largest capacity of your system file, it is possible to have problems with table dump to a single file, and Split is used to divide.

% PG_Dump DBNAME | SPLIT -B 1M - FileName.dump.

Reload

% CreatedB DBName

% cat filename.dump. * | PGSQL DBNAME

Name: Touch

Use permission: All users

Use mode:

Touch [-ACFM]

[-r reference-file] [--file = reason "File]

[-t mmddhhmm [cc] yy] [. ss]

[-d Time] [--DATE = TIME] [--Time = {Atime, Access, Use, Mtime, Modify}]

[--NO-CREATE] [--HELP] [--Version] file1 [file2 ...]

Description:

Touch command changes the time record of the file. LS -L can display the time record of the file.

parameter:

a Changing the read time record of the file.

m change the modification time record of the file.

C If the purpose file does not exist, it will not establish a new file. Like -No-Create.

F is not used, is to retain to compatibility with other UNIX systems.

r Use the reference file time record, like the effect of thefile.

D Setting time and ****, you can use a variety of different formats.

T Time Record of the file is set, the format is the same as the DATE instruction.

--NO-CREATE does not establish a new file.

--Help lists the instruction format.

--Version lists this message.

example:

The simplest way of use, change the file when you record the time. If the file does not exist, a new file will be established.

Touch file

TOUCH file1 file2

Change the time record of File to 18:3:39 on May 6, 2,000 years. Time format can refer to the Date directive, at least you need to enter MMDDHHMM, which is the time of months and minutes.

Touch -c -t 05061803 file

Touch -c -t 050618032000 file

Change the File time record into ReferenceFile.

Touch -R ReferenceFile File

The time record of File is changed to 18:3:36 on May 6, two thousand years old. Time can be used in AM, PM or 24-hour format, and other formats can be used in other formats such as 6 May 2000.

Touch -d "6:03 pm" file

Touch -d "05/06/2000" File

Touch -d "6:03 PM 05/06/2000" File

Name: AT

Use permission: All users

How to use: At -V [-q queue] [-f file] [-mldbv] Time

Description: AT allows the user to specify a certain number or instruction in Time, TIME's format is HH: mm, the HH of HH is hour, MM is minutes, or you can specify AM, PM, Midnight, Noon, Teatime (is 4 pm).

If you want to specify the time in more than a day, you can use mmddyy or mm / dd / yy format, where mm is minute, DD is the day, yy refers to the year. In addition, the user can even use a NOW time interval to elastic designation time, where the interval can be Minutes, Hours, Days, Weeks

In addition, the user can also specify Today or Tomorrow to represent today or tomorrow. When the time is specified and press Enter, the AT will enter the conversation mode and ask for input instructions or programs. When you press CTRL D, press Ctrl D to complete all the actions, as for the result of the execution, will be sent back to your account .

Tie count:

-V: Print Publication No.

-q: Use the specified column (queue) to store, the data of the AT is stored in the so-called queue, and the user can use multiple queue at the same time, and the number of Queue is A, B, C ... Z, and A 52 in total, B, ... Z

-m: If there is no output result after the program / instruction is executed, it is also necessary to send a letter to the user.

-f file: Read the pre-written command file. Users do not have to use the conversation mode to enter, first write all the specified first to the file again, read -l: List all the specified (the user can also use ATQ directly without using AT -L)

-d: Delete design (can also use ATRM directly without AT -D)

-v: list all specified that has been completed but has not been deleted

Example:

5 pm after three days of execution / bin / ls:

AT 5PM 3 days / bin / ls

5 pm after three weeks of performed / bin / ls:

AT 5PM 2 Weeks / Bin / LS

Tomorrow's 17:20 execution / bin / date:

At 17:20 Tomorrow / BIN / DATE

The last day of 1999 printing the end of world!

At 23:59 12/31/1999 echo the end of world!

Name: CAL

Use permission: All users

How to use: Cal [-mjy] [MONTH [YEAR]

Description:

Display calendar. If there is only one parameter, it represents the year (1-9999), showing the annual calendar. It must be written in the year: `` Cal 89 / will not show the calendar of 1989. Use two parameters, indicating the month and year. If there is no parameter, this month's calendar is displayed.

September 3rd on September 1752, the Western calendar, because most countries used a new calendar, 10 days of removal, so the monthly calendar of the month is somewhat different. It was before this.

匡 兜 

-M: Displayed on weekdays for weekly first day.

-J: Displayed by Kaisa, that is, the number of days from January 1 is displayed.

-y: Show this year calendar.

example:

CAL: Shows the monthly calendar of this month.

[root @ mylinux / root] # Date

Tue aug 15 08:00:18 CST 2000

[root @ mylinux / root] # CAL

August 2000

Su Mo Tu We TH fr SA

1 2 3 4 5

6 7 8 9 10 11 12

13 14 15 16 17 18 19

20 21 22 23 24 25 26

27 28 29 30 31

[root @ MYLINUX / root] #

CAL 2001: Shows the annual calendar of AD.

[root @ MYLINUX / ROOT] # CAL 2001

2001

January February March

Su Mo Tu We TH fr Su Mo Tu We TH fr sa

1 2 3 4 5 6 1 2 3 1 2 3

7 8 9 10 11 12 13 4 5 6 7 8 9 10 4 5 6 7 8 9 10

14 15 16 17 18 19 20 11 14 16 17 11 12 13 14 15 16 17

21 22 23 24 25 26 27 18 19 20 21 22 23 24 18 19 20 21 22 23 24

28 29 30 31 25 26 27 28 25 26 27 28 29 30 31

April May June

Su Mo Tu We TH fr Su Mo Tu We TH fr sa

1 2 3 4 5 6 7 1 2 3 4 5 1 2

8 9 10 11 12 13 14 6 7 8 9 10 11 12 3 4 5 6 7 8 9

15 16 17 18 19 20 21 14 15 16 17 18 19 10 11 12 13 14 15 16

22 23 24 25 26 27 28 20 21 222 23 24 25 26 17 18 19 20 21 22 2329 30 27 28 29 30 31 24 25 26 27 28 29 30

July August September

Su Mo Tu We TH fr Su Mo Tu We TH fr sa

1 2 3 4 5 6 7 1 2 3 4 1

8 9 10 11 12 13 14 5 6 7 8 9 10 11 2 3 4 5 6 7 8

15 16 17 18 19 20 21 12 14 15 16 17 18 9 10 11 12 13 14 15

22 23 24 25 26 27 28 19 20 21 22 23 24 25 16 17 18 19 20 21 22

29 30 31 26 27 28 29 30 31 23 24 25 25 26 27 28 29

30

October November DecEmber

Su Mo Tu We TH fr Su Mo Tu We TH fr sa

1 2 3 4 5 6 1 2 3 1

7 8 9 10 11 12 13 4 5 6 7 8 9 10 2 3 4 5 6 7 8

14 15 16 17 18 19 20 13 14 16 17 9 10 11 12 13 14 15

21 22 23 24 25 25 26 27 18 19 20 21 22 23 24 16 17 18 19 20 21 22

28 29 30 31 25 26 27 28 29 30 23 24 25 26 27 28 29

30 31

[root @ MYLINUX / root] #

CAL 5 2001: Shows AD in May 2001.

[root @ MYLINUX / ROOT] # CAL 5 2001

May 2001

Su Mo Tu We TH fr SA

1 2 3 4 5

6 7 8 9 10 11 12

13 14 15 16 17 18 19

20 21 22 23 24 25 26

27 28 29 30 31

[root @ MYLINUX / root] #

Cal -m: The first day of week is the week, showing this month.

[root @ mylinux / root] # Cal -m

August 2000

Mo Tu We TH fr SU

1 2 3 4 5 6

7 8 9 10 11 12 13

14 15 16 17 18 19 20

21 22 23 24 25 26 27

28 29 30 31

[root @ MYLINUX / root] #

Cal -jy: Displays the number of days from January 1st.

[root @ MYLINUX / ROOT] # Cal -jy

2000

January February

Sun Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed Thu Fri Sat

1 32 33 34 35 36

2 3 4 5 6 7 8 37 38 39 40 41 42 43

9 10 11 12 13 14 15 44 45 46 47 48 49 50

16 17 18 19 20 21 22 51 52 53 54 55 56 57

23 24 25 26 27 28 29 58 59 60

30 31

March April

Sun Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed Thu Fri Sat

61 62 63 64 92

65 66 67 68 69 70 71 93 94 95 96 97 98 99

72 73 74 75 76 77 78 100 101 102 103 104 105 10679 80 81 82 83 84 85 107 108 109 110 111 112 113

86 87 88 89 90 91 114 115 116 117 118 119 120

121

May June

Sun Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed Thu Fri Sat

122 123 124 125 126 127 153 154 155

128 129 134 131 132 133 134 156 157 158 159 160 161 162

135 136 137 138 139 140 141 163 164 165 166 167 168 169

142 143 144 145 146 147 148 170 171 172 173 174 175 176

149 150 151 152 177 178 179 180 181 182

July August

Sun Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed Thu Fri Sat

183 214 215 216 217 218

184 185 186 187 188 189 190 219 220 221 222 223 224 225

191 192 193 194 195 196 197 226 227 228 229 230 231 232

198 199 200 201 202 203 204 233 237 238 239

205 206 207 208 209 210 211 240 241 242 243 244

212 213

September October

Sun Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed Thu Fri Sat

245 246 275 276 277 278 279 280 281

247 248 249 250 251 252 253 282 283 284 285 286 287 288

254 255 256 257 258 259 260 289 290 291 292 293 294 295

261 262 263 264 265 266 267 296 297 298 299 300 301 302

268 269 270 271 272 273 274 303 304 305

November december

Sun Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed Thu Fri Sat

306 307 308 309 336 337

310 311 312 313 314 315 316 338 339 340 341 342 343 344

317 318 319 320 321 322 323 345 346 347 348 349 350 351

324 325 326 327 328 329 330 352 353 354 355 356 357 358

331 332 333 334 335 359 360 361 362 363 364 365

366

[root @ MYLINUX / root] #

Name: crontab

Use permission: All users

Use mode:

Crontab [-U user] filecrontab [-u user] {-l | -r | -e}

Description:

Crontab is used to use the user at a fixed time or a fixed interval execution, in other words, that is, the like's schedule. -u user refers to the schedule that sets the specified user. This premise is that you have to have its permissions (such as root) to specify the schedule of others. If you don't use -u user, it means to set your own schedule.

Number of meals:

-e: Perform a text editor to set a time program, the contents of the text editor is VI. If you want to use the other text editor, please set the Visual environment variable to specify the use of that text editor (for example STENV Visual Joe) -r: Delete the current Turkey

-L: List the current schedule

The format of the schedule is as follows:

F1 F2 F3 F4 F5 Program

Where F1 is a minute, F2 represents hours, and F3 represents the first few days in one month, and F4 represents the month, F5 represents the first few days in the week. Program represents the program to be executed.

When F1 is *, it is indicated that the program is executed every minute, and the F2 is *, it is executed per hour, and the remaining classes are pushed.

When F1 is A-B, it is performed from step a minutes to the second minute. When F2 is A-B, it is to be executed from paragraphs A to B.

When F1 is * / n, each time interval is executed once, F2 is * / N to execute once a time interval per n, and the remaining classes push

When F1 is A, B, C, ... is shown in paragraph A, B, C, ... minutes to perform, F2 is A, B, C, ... indicated first, b, c ... Hourly to be executed, the rest

Users can also store all settings first in the file file, and set the time schedule in the way in the CRONTAB FILE.

Example:

Perform an hour per hour per hour / bin / ls:

0 7 * * * / bin / ls

In December, 6:00 pm every day, per 20 minutes, per 20 minutes, / usr / bin / backup:

0 6-12 / 3 * 12 * / usr / bin / backup

On Monday to Friday, send a letter to alex@domain.name on Monday to Friday.

0 17 * * 1-5 Mail -s "hi" alex@domain.name

0:20 points per day, 2:20, 4:20, 4:20 .... Executive Echo "Haha"

20 0-23 / 2 * * * Echo "Haha"

Note:

After executing the time you specified, the system will send you a letter to you, show the program executed, if you don't want to receive such a letter, please add> / dev after each line of empty / NULL 2> & 1.

Name: Date

Use permission: All users

Use mode:

Date [-u] [-d datestr] [-s datestr] [--UTC] [--Universal] [--date = datestr] [--SET = DATESTR] [--help] [--version] [ FORMAT] [MMDDHMM [CC] YY] [. ss]

Description:

Date can be used to display or set the date and time of the system. In the display, the user can set the format that wants to display, the format is set to a plurality of plus numbers, where the available tag list is as follows:

Time:

%: Print%

% N: Next line

% T: jumping

% H: Hours (00....

% I: Hours (01..12)

% K: Hours (0..23)

% L: Hours (1..12)

% M: Minutes (00..59)

% P: Display Local AM or PM

% R: Direct display time (12 hours, format HH: mm: ss [ap] M)

% S: From January 1, 1970 00:00 UTC to the number of seconds

% S: second (@ 10)

% T: Direct display time (24-hour system)

% X: equivalent to% h:% m:% s

% Z: Show time zone

Date:

% A: Sun..sat

% A: Sunday..SATURDAY

% B: Month (Jan..dec)

% B: January..DECEMBER

% C: Direct display date and time

% D: Japan (01..31)

% D: Direct Display Date (mm / DD / YY)

% H: same% B

% J: The first day of the year (001..366)

% M: Month (01..12)

% U: The first day of the year (00..53) (the first day of Sunday is one week)

% W: The first day of the week (0..6)

% W: The first day of the year (00..53) (in the first day of Monday)

% x: Direct display Date (mm / dd / yy)

% Y: The last two digits of the year (00.99)

% Y: Complete Year (0000..9999)

If it does not start with the plus sign, it means to set the time, and the time format is MMDDHHMM [CC] YY] [. SS], where mm is month, DD is the day, HH is hour, MM is a minute, CC is the year The first two digits, YY is two digits after the year, SS is the number of seconds.

Tie count:

-d DateStr: Displays the time set in DateStr (non-system time)

--help: Display auxiliary message

-s datestr: Set the time set to the time set in DateStr

-u: Show current Greenwich Time

--Version: Display version number

Example:

During the display time, the time is jumped, then display the current date:

Date % T% N% D

Display months and days:

Date % B% D

Display date and set time (12:34:56):

Date --Date 12:34:56

Note:

When you don't want to have meaningless 0 (for example, 1999/03/07), you can insert - symbols in the mark, such as Date % - H:% - M:% - S will not be in seconds The meaning of the meaning is removed, like the original 08:09:04 will be changed to 8: 9: 4. In addition, only the permissions (such as ROOT) can set the system time.

When you change the system time with the root identity, please write the system time in CMOS in CLOCK -W so that the system time will continue to hold the latest correct value when it is rebooted next time.

Name: SLEEP

Use permission: All users

How to use: Sleep [--help] [--version] Number [SMHD]

Description: Sleep can be used to delay the current action for a while

Parameter Description :

--help: Display auxiliary message

--Version: Display version number

Number: Time length, back can be connected to S, M, H or D

Where S is second, m is minutes, H is hour, D is the number of days

Example:

Shows the current time after 1 minute, then display time again:

Date; Sleep 1M; Date

Name: Time

Use permission: All users

How to use: Time [Options] Command [arguments]

Description: The use of the Time command is information such as time and system resources that measure the time and system resources required for specific instructions. For example, CPU time, memory, input and the like, and the like. Special attention is required is that some information can not be displayed on Linux. This is because the allocation of some resources on Linux is not the same as the TIME instruction, so that the TIME instruction cannot be obtained.

Put on

-o or --Output = file

Set the result output file. This option writes the output of the Time to the specified file. If the file already exists, the system will override its content. -a or --append

With -O use, the result will be written to the end of the file without overwriting the original content.

-f format or - format = format

Set the display mode with the Format string. When this option is not set, you will use the system preset format. However, you can use the environment variable time to set this format, so you don't have to set it once every login system.

Generally set, you can use

/ t

Indicates the jump, or use

/ N

Reverse the wrap. Each material uses% as a preamble. If you want to use a percentage symbol in the string, use it. (People who have learned C language will feel very familiar)

There are four major items that the TIME instructions can display, namely:

Time Resources

Memory Resources

IO Resources

Command info

The detailed content is as follows:

Time Resources

E Execute the time spent, the format is: [Hour]: minute: second. Note that this number does not represent the actual CPU time.

e Execute the time spending the instruction, the unit is second. Note that this number does not represent the actual CPU time.

The time spent on the core mode during the execution of the S command is seconds.

U The time spent in the user mode during execution, the unit is second.

P Execute the occupation ratio of the CPU when the command is executed. In fact, this number is the core mode plus the CPU time of the user mode divided by total time.

Memory Resources

M The maximum value of the entity memory occupied during execution. Unit is KB

T execute the average value of the entity memory occupied, the unit is KB

K The total amount of memory (Stack Data Text) occupied by the K executive program is KB.

D Executive Program The average size of the unshared data area, the unit is KB

P Execute the average size of the unshared stack, the unit is KB

X The average of the shared text is executed, and the unit is KB

The size of the Z system memory page is byte. This is a constant for the same system.

IO Resources

F This program's main memory page error occurrence number. The so-called main memory page error is that a memory page has been replaced into the SWAP file and has been assigned to other programs. At this point, the content of this page must be read again from the replacement.

R The number of times the secondary memory page of this program is incorrect. The so-called secondary memory page error is that although the memory page has been replaced into the replacement file, it is not allocated to other programs. At this point, the content of this page is not broken, and it is not necessary to read it from the replacement.

W This program is swapped to the number of replacement files

C This program is forced to interrupt (like the distributed CPU time is exhausted)

W This program voluntarily disrupts (like the number of I / O execution, like a disk read, etc.)

I number of files entered by this program

O number of files outputted by this program

r Socket Message received by this program

s Socket Message sent by this procedure

K This program received by the signal (Signal)

Command info

C Execution parameters and instruction name

X command end code (exit status)

-p or --portability

This option will automatically set the display format as: Real% E

User% u

SYS% S

The purpose of this is to compat with the POSIX specifications.

-v or --verbose

This option will list the resources used in all programs, not only, as well as general English statements, but also instructions. People who don't want to spend time to set or just start to contact this instruction is quite useful.

example:

Use the following instructions

Time -V PS -AUX

We can get the results of PS -AUX and the system resources taken. As listed below:

User PID% CPU% MEM VSZ RSS TTY Stat Start Time Command

Root 1 0.0 0.4 1096 472? s APR19 0:04 Init

Root 2 0.0 0.0 0 0? SW APR19 0:00 [KFlushd]

Root 3 0.0 0.0 0 0? SW APR19 0:00 [KPIOD]

......

Root 24269 0.0 1.0 2692 996 PTS / 3 r 12:16 0:00 ps -aux

Command being timed: "ps -aux"

User Time (Seconds): 0.05

System Time (Seconds): 0.06

Percent of CPU this Job Got: 68%

Elapsed (Wall Clock) Time (H: MM: SS OR M: SS): 0: 00.16

Average Shared Text Size (KBYTES): 0

Average unshared data size (kbytes): 0

Average stack size (kbytes): 0

Average Total Size (KBYTES): 0

Maximum Resident Set Size (KBYTES): 0

Average Resident Set size (kbytes): 0

Major (Requiring I / O) Page Faults: 238

Minor (Reclaiming A Frame) Page Faults: 46

Voluntary Context Switches: 0

Involuntary Context Switches: 0

SWAPS: 0

FILE SYSTEM INPUTS: 0

File System Outputs: 0

Socket Messages SENT: 0

Socket Messages Received: 0

Signals Delivered: 0

Page Size (bytes): 4096

EXIT STATUS: 0

Name: uptime

Use permission: All users

How to use: uptime [-v]

Description: Uptime provides the following information, no other parameters:

Current time

The system is turned on to the time

The number of users connected

Recently, five minutes and fifteen minutes of system load

Parameters: -v Displays version information.

Example: uptime

The result is:

10:41 AM UP 5 Days, 10 min, 1 Users, Load Average: 0.00, 0.00, 1.99

Name: CHFN

Use permission: All users

Usage: shell >> CHFN

Description: Provide users to change individual information for Finger and Mail UserName

example:

Shell >> CHFN

Changing Finger Information for User

Password: [del] name []: johnney huang ### provides information when providing finger

Office []: NCCU

Office phone []: [DEL]

Home phone []: [DEL]

Name: chsh

Use permission: All users

Usage: shell >> Chsh

Description: Change the user shell setting

example:

Shell >> Chsh

Changing Fihanging Shell for User1

Password: [DEL]

New shell [/ bin / tcsh]: ### [is currently used by Shell]

[DEL]

Shell >> Chsh -l ### 展 / / etc / shells archive content

/ BIN / BASH

/ bin / sh

/ BIN / ASH

/ bin / bsh

/ bin / tcsh

/ bin / csh

Name: Finger Use Permissions: All users

How to use: finger [Options] user [@address]

Note: Finger allows the user to query some other user's information. The information that will be listed is:

Login Name

User name

Home Directory

Shell

Login Status

Mail status

.plan

.project

.forward

Where. PLAN, .Project and .Forward are the data in the file in his Home Directory. ProWard, etc. If there is no. The Finger directive is not limited to queries on the same server, or you can find users on a remote server. Just give an address like an e-mail address.

Put on

-L

Multi-line display.

-S

Single line display. This option only displays the login name, real name, terminal name, idle time, login time, office number, and phone number. This option is invalid if the user is the user of the remote server.

Example: The following instructions can check the information of this machine:

Finger root

The results are as follows:

Login: root name: root

Directory: / root shell: / bin / bash

NEVER Logged IN.

No Mail.

NO PLAN.

Name: Last

Use permission: All users

How to use: shell >> Last [Options]

Explanation: The display system has been a message from the beginning of the month.

Put on

-R 省 Hostname's field

-Num show before NUM

UserName display UserName login message

TTY restriction login message contains terminal code

example:

Shell >> Last -R-2

Johnney PTS / 1 MON AUG 14 20:42 STILL Logged in

Johnney PTS / 0 MON AUG 14 19:59 Still Logged in

WTMP Begins Tue Aug 1 09:01:10 2000 ### / var / log / wtmp

Shell >> Last -2 Minery

Minery PTS / 0 140.119.217.115 MON AUG 14 18:37 - 18:40 (00:03)

Minery PTS / 0 140.119.217.115 Mon Aug 14 17:22 - 17:24 (00:02)

WTMP Begins Tue Aug 1 09:01:10 2000 Name: Login

This order will not be done! Oh, I am not here, I have a push ink to delay everyone's beautiful youth ^ _ ^

Name: Passwd

Use permission: All users

How to use: Passwd [-k] [-l] [-u [-f] [-d] [-s] [username]

Description: Used to change the password of the user

parameter:

-k

-L

-u

-f

-d Close the user's password authentication function, the user will not be able to enter a password when logging in, and only the user who has root privileges can be used.

-S Displays the specified user's password authentication species, only the user who has root privileges can be used.

[username] Specifies the account name.

Name: WHO

Use power line: All users can use

How to use: WHO - [husfv] [user]

Note: There are those users in the display system being on, and the data displayed contains the user ID, the terminal used, connected from there, online time, lag time, CPU usage, action, etc.

Tie count:

-h: Do not display the title column

-u: Do not display user action / work

-s: Show with short format

-f: Do not display the user's online location

-V: display program version

Name: / etc / aliases

Use permission: System managers

How to use: please update your database with newaliases

Description:

Sendmail uses an action that is converted by the user name in / etc / aliases. When sendmail receives a letter to XXX, it will be given to another by the content of the AliaSS file. This feature creates a user who is only valid in the letters system. For example, Mailing List uses this feature. In MailingList, we may create a mailingList called Redlinux@link.ecpi.edu, but actually doesn't have a user named RedLinux. The actual AliaSS file is to receive the Mailing List processing of the Mailing List processing.

/ etc / aliases is a file file, Sendmail requires a binary format /etc/aliases.db. NEWALIASES's functional is to convert / etc / aliases into a repository that SENDMAIL can understand. example:

# newaliases

The following command will do the same thing.

# sendmail -bi

Related commands:

Mail, Mailq, Newaliases, Sendmail

"Mail [Back]

Name: Mail

Use permission: All users

How to use: mail [-iinv] [-S Subject] [-c cc-addr] [-b bcc-addr] user1 [user 2 ...]

Description:

Mail is just a directive, Mail is also an email program, but people who use Mail to read the letter should be very small! For system managers, Mail is useful, because managers can write to Script with Mail, regularly send some memorandum of reminder systems.

parameter:

i ignore the interrupt signal of TTY. (Interrupt)

I forced set into interactive mode. (Interactive)

v prints the message, such as the location of the send letter, state, and the like. (Verbose)

n Do not read the mail.rc setting file.

S Mail title.

C CC mail address.

B BCC email address.

example:

Get the letter to one or more email addresses, because no other options are added, the user must enter the contents of the title and the letter. User2 does not have a host position, it will be given to the user2 user of the mail server. Mail User1@email.address

Mail User1@email.address user2

Sending the content of mail.txt to user2 simultaneously CC to USER1. If you set this line instruction to cronjob, you can send a memo to the system user.

Mail -s Title - C User1 USER2

Directive: MESG

Use permission: All users

How to use: MESG [y | n]

Explanation: Decide whether other people are allowed to get to their end-machine interface

Y: Allow messages to the terminal interface.

n: Do not allow messages to the terminal interface.

If there is no setting, the message delivery is fixed by the terminal interface.

Example:

Changing the current message settings, modification is not allowed to pass on the terminal interface:

MESG N

Directives related to MESG are: Talk, Write, Wall.

Name: / etc / aliases

Use permission: System managers

How to use: newaliases

Description:

Sendmail uses an action that is converted by the user name in / etc / aliases. When sendmail receives a letter to XXX, it will be given to another by the content of the AliaSS file. This feature creates a user who is only valid in the letters system. For example, Mailing List uses this feature. In MailingList, we may create a mailingList called Redlinux@link.ecpi.edu, but actually doesn't have a user named RedLinux. The actual AliaSS file is to receive the Mailing List processing of the Mailing List processing.

/ etc / aliases is a file file, Sendmail requires a binary format /etc/aliases.db. NEWALIASES's functional is to convert / etc / aliases into a repository that SENDMAIL can understand.

Parameters: No parameters. example:

# newaliases

The following command will do the same thing.

# sendmail -bi

Related commands:

Mail, Mailq, Newaliases, Sendmail

Name: Talk

Use permission: All users

Use mode:

Talk Person [TTYNAME]

Description: Talk to other users

Tie count:

Person: The user account for the interpretation, if the user can enter Person@machine.name on other machines

TTYNAME: If the user has more than two TTY connectors, you can choose the right TTY message.

Example. 1:

Talking to the user rolland on the machine now, and Rolland has only one connection:

Talk Rolland

The next step is to respond, if rollaend accepts, RollaEnd Enter the `Talk Jzlee`, you can start talking, press CTRL C.

Example. 2: Talk to the user rolland on Linuxfab.cx, use PTS / 2 to talk:

Talk rollaend@linuxfab.cx PTS / 2

The next step is to respond, if rollaend accepts, RollaEnd Enter the `Talk Jzlee @ Jzlee.home`, you can start talking, press Ctrl C to pay attention: If the word of the screen appears abnormal character, try Press CTRL L to update the screen screen.

Name: Wall

Use permission: All users

Use mode:

Wall [Message]

Instructions for use:

Wall transmits the message to each MESG to be set to YES. When using the terminal interface as standard, add EOF (usually using Ctrl D) 

Example:

Communication "hi" gives each user:

Wall Hi

Name: Write

Use permission: All users

Use mode:

Write user [TTYNAME]

Description: Communication to other users

Tie count:

User: User account for preparing message

TTYNAME: If the user has more than two TTY connectors, you can choose the right TTY message.

Example. 1:

The news is given to Rolland, and the Rolland has only one connection:

Write rolland

The next is to hit the message, please press CTRL C.

Example .2: Communication to Rolland, rolland's connection with PTS / 2, PTS / 3:

Write RollaEnd PTS / 2

The next is to hit the message, please press CTRL C.

Note: If the other party sets MESG N, the interpretation will not pass to the other party.

Name: kill

Use permission: All users

Use mode:

Kill [-siGnal | -p] [-a] PID ...

Kill -l [Signal]

Description: KILL sends a specific signal (Signal) to the stroke of the stroke ID, as a specific action based on this signal, if not specified, the preset is a signal to be terminated (TERM)

Put on

-S (Signal): Among them, the signals are HUP (1), KILL (9), TERM (15), which represents heavy run, cut off, end; detailed signals can be used with kill -l

-p: Print PID, does not send the signal

-L (Signal): List all available signal names

example:

Cut the PID 323 stroke (kill):

KILL-9 323

Running the PID 456 (Restart):

Kill-Hup 456

Name: Nice

Use permission: All users

How to use: nice [-n adjustment] [-adjustment] [--adjustment = adjustment] [--help] [--version] [Command [arg ...]

Description: Execute the program with a changed priority, if not specified, print the current scheduled priority, the internal Adjustment is 10, the range is -20 (highest priority) to 19 (minimum priority)

Put on

-n Adjustment, -adjustment, --adjustment = Adjustment is an increase in Adjustment to this original priority?

--help display help message

--Version Display Version Information

example:

Put the priority of the LS 1 and execute:

Nice -n 1 ls

Add 10 priority to 10 and execute:

Nice LS adds the priority of the LS 10 and execute

Note: Priority is used for the job system to determine the parameters assigned by the CPU. Linux uses the "Round-Robin" to do the CPU schedule, the higher the priority, the cpu time that may be obtained more. Name: PS

Use permission: All users

How to use: ps [options] [--help]

Description: Show the dynamics of the moment

parameter:

There are a lot of PS parameters, and only several common parameters are listed here and

-A lists all itinerary

-W Display widened can display more information

-au shows more detailed information

-AUX shows all strokes that contain other users

Au (x) output format:

User PID% CPU% MEM VSZ RSS TTY Stat Start Time Command

User: Tour owner

PID: PID

% CPU: Used CPU usage

% MEM: Occupation Memory Use

VSZ: The size of the virtual memory occupied

RSS: The size of the memory

TTY: The secondary device number of the terminal (Minor Device Number Of TTY)

Stat: The status of this trip:

D: I / O action in uninterrupted still (通 □ □ 缜 B)

R: is being executed

S: Static state

T: Pause

Z: No existence but temporarily unable to eliminate

W: There is not enough memory paging to allocate

<: High priority stroke

N: low priority stroke

L: There is a memory paging assignment and lock in memory (instant system or A I / O)

START: Time of the trip

Time: Time to do

Command: Directive executed

example:

PS

PID TTY TIME CMD

2791 TTYP0 00:00:00 TCSH

3092 TTYP0 00:00:00 PS

% PS -A

PID TTY TIME CMD

1? 00:00:03 init

2? 00:00:00 Kflushd

3? 00:00:00 Kpiod

4? 00:00:00 Kswapd

5? 00:00:00 MDRECoveryd

.......

% PS -AUX

User PID% CPU% MEM VSZ RSS TTY Stat Start Time Command

Root 1 0.0 0.7 1096 472? S Sep10 0:03 init [3]

Root 2 0.0 0.0 0 0? SW SEP10 0:00 [KFLUSHD]

Root 3 0.0 0.0 0 0? SW SEP10 0:00 [KPIOD]

Root 4 0.0 0.0 0 0? SW SEP10 0:00 [KSWAPD]

........

Name: PStree

Use permission: All users

Use mode:

PStree [-a] [-c] [-h | -hpid] [-l] [-n] [-p] [-u] [-g | -u] [pid | user]

PStree -V

Description: Display all the strokes in a tree map, the tree map will be PID (if there is specified) or in init this basic stroke (root), if there is a specified user ID, the tree map will only display The trip owned by the user

parameter:

-a Displays the full instructions and parameters of the itinerary, if it is replaced by the memory body, add parentheses

-c If there is a rebounded stroke name, it is listed separately (the preset value will be added in front *

example:

PStree

INIT - - AMD

| -apmd

| -ATD

| -httpd --- 10 * [httpd]

% PStree -P

INIT (1) - - AMD (447)

| -apmd (105)

| -ATD (339)

% PStree -C

INIT - - AMD

| -apmd

| -ATD

| -HTTPD - - httpd | | -httpd

| | | -HTTPD

| | | -HTTPD

....

Name: renice

Use permission: All users

How to use: renice priority [-p] pid ...] [-g] pgrp ...] [-u] user ...]

Explanation: Refaten a priority of one or more strokes (one or more will depend on the above parameters)

Put on

-p PID re-specifies the priority of the Id of the stroke to PID

-g PGRP re-specifies the priority of the ID of the stroke group (one or more) of PGRP (one or more)

-u User re-specifies priority for the stroke owner for the User

example:

Plus the stroke ID of 987 and 32 and the priority number of the stroke owner is Daemon and root plus 1:

RENICE 1 987 -U daemon root -p 32

Note: Each trorate has a unique ID 

Name: TOP

Use permission: All users

How to use: TOP [-] [D DELAY] [q] [c] [s] [s] [n]

Explanation: Display Process dynamics instantly

Put on

D: Change the displayed update speed, or press S in the Trolver Command Column (Interactive Command)

Q: There is no delay display speed. If the user is the permissions of superUser, the top will execute at the highest priority.

C: Switch the display mode, there are two modes, one is only the name of the execution file, the other is to display the full path and the name S: cumulative mode, the subunion of the completion or disappear, the dead product CPU Time accumulate

S: Safety mode, cancel the conversation instruction, avoid potential crisis

i: No idle (IDLE) or useless (Zombie) stroke

N: Update the number of times, will exit TOP after completion

B: Batch file mode, with "N" parameters, can be used to output the result of TOP to the file

example:

Show out ten times after ten times;

TOP-N 10

The user will not use the conversation instruction to the stroke command:

Top -s

Enter the update display twice into the file name to top.log:

TOP-N 2 -B

Name: Skill

Use permission: All users

How to use: skill [signal to send] [options] Select the rules of the program

Description:

Send a signal to the executable program, the preset message is Term (interrupt), the more often used information is HUP, INT, KILL, STOP, CONT, and 0

The message has three ways: -9, -sigkill, -kill, can use -l or -l already listed the available messages.

General parameters:

-f fast mode / has not been completed

-i interactive mode / each action will be confirmed

-V Detailed output / list of selected programs

-w Intelligent warning message / has not been completed

-n no action / display program code

Parameters: The rules of the selection can be that the terminal code, the user name, the program code, the command name.

-T Terminal Code (TTY or PTY)

-u user name

-P program code (PID)

-c Command Name You can use the signal:

The known signal name, signal code, and function will be listed below.

Name (code) function / description

ALRM 14 leaves

HUP 1 leave

INT 2 leave

Kill 9 leaves / forced close

PIPE 13 leaves

Poll leaves

PROF leaves Term 15 leaves

USR1 leaves

USR2 leaves

VTALRM leaves

STKFLT leaves / only for I386, M68K, ARM, and PPC hardware

Unused leaves / only for I386, M68K, ARM, and PPC hardware

TSTP stop / generate behavior related to content

TTIN stop / generate behavior related to content

Ttou stop / generate behavior related to content

STOP stop / forced shutdown

CONT From the new start / if the stop state is started, otherwise ignore

PWR ignores / leave in some systems

Winch ignores

CHLD ignores

ABRT 6 core

FPE 8 core

Ill 4 core

Quit 3 core

SEGV 11 core

TRAP 5 core

SYS core / perhaps no actual

EMT core / perhaps no actual

BUS core / core failure

XCPU core / core failure

XFSZ core / core failure

example:

Stop all programs on the PTY device

Skill -kill -v PTS / *

Stop three users USER1, USER2, USER3

Skill -stop User1 User2 USER3

Other related commands: kill

Name: EXPR

Use permission: All users

### String length

Shell >> EXPR Length "this is a test"

14

### Digital Commercial Number

Shell >> EXPR 14% 9

5

### From the location

Shell >> EXPR SUBSTR "this is a test" 3 5

IS IS

### Digital Skewers Only The First Character

Shell >> Expr Index "Testforthegame" e

2

### String truly reproduced

Shell >> EXPR Quote THISATSTFORMELA

ThisisatestFormela

Name: TR

### 1. Compare to the part to change all uppercase files in the directory to lowercase files?

There seems to be many ways, "TR" is one of them:

#! / bin / sh

DIR = "/ tmp / testdir";

Files = `Find $ DIR -TYPE F`;

For i in $ files

DO

Dir_name = `Dirname $ I`;

Ori_filename = `basename $ I`

NEW_FILENAME = `Echo $ Ori_FileName | TR [: Upper:] [: Lower:]`> / dev / null;

#echo $ new_filename;

MV $ DIR_NAME / $ Ori_FileName $ DIR_NAME / $ New_FILENAME

DONE

### 2. ourselves ... LowerCase to Uppercase

Tr Abcdef ... [del] Abcde ... [DEL]

TR A-Z A-Z

Tr [: Lower:] [: Upper:]

Shell >> Echo "this is a test" | TR A-Z A-Z> WWW

Shell >> Cat WWW

This is a test

### 3. Remove the string of unwanted

Shell >> Tr -d this ### Remove about T.E.S.T

THIS

MAN

MAN

Test

e

### 4. Replace strings

Shell >> Tr -s "this" "test"

THIS

Test

TH

TE

Directive: CLEAR

Uses: Clear the screen.

How to use: Enter clear on Console.

Name: Reset, Tset

How to use: tset [-iqqrs] [-] [-e ch] [-i ch] [-k ch] [-m mapping] [Terminal]

Instructions for use:

Reset actually and tset is a command that is the purpose of setting the terminal. In general, this command will automatically determine the current terminal of the current terminal from the environment variable, command column, or other configuration. If the specified type is?, This program will ask the user to enter the terms of the terminal.

Since this program sets back the terminal back to the original state, in addition to the use of login, when the system terminal enters some strange states because the program is not properly executed, you can also use it to reset the terminal O, for example Be careful to enter the binary file with the CAT directive to the terminal, often there is a terminal that does not respond to the keyboard input, or responds to some strange characters. You can reply to the original state with RESET. Option Description:

-p

Display the terminal category on the screen, but do not make the set action. This command can be used to achieve the category of the current terminal.

-e ch

Set the ERASE unit into CH

-i ch

Set the interrupt character to CH

-k ch

Will delete a line of characters set to Ch

-I

Don't do settings, if you don't use the option -Q, the current value of Erase, interrupts and delete characters will still be sent to the screen.

-Q

Do not display ERASE, interrupt and delete the value of the character to the screen.

-r

Print the terminal machine class on the screen.

-S

Send the type of command to the setting TERM to the terminal, usually used in .login or .profile

example:

Let the user enter a terminal model and set the terminal to the type other preset state.

# RESET?

Set the ERASE character set Control-h

# RESET -E ^ B

Display the string of the setting on the screen

# reset -s

ERASE IS Control-B (^ b).

Kill IS Control-U (^ U).

Interrupt IS Control-C (^ c).

Term = xterm;

Name: Compress

Use permission: All users

How to use: Compress [-dfvcv] [-B Maxbits] [file ...]

Description:

Compress is a fairly ancient UNIX file compression instruction. The compressed file will add a .z extended file name to distinguish uncompressed files, compressed files can be decompressed in uncompress. To press the plurality of files into a compressed file, you must first turn the archive Tar and then compress. Since Gzip can generate more ideal compression ratios, the general people have changed more Gzip to archive compression tools.

parameter:

C Output results to standard output equipment (general refers to the screen)

F forced writing to the file, if the destination already exists, it will be overwritten (Force)

v The message executed by the program on the screen (Verbose)

b Set the upper limit of the number of common strings, calculate with bit yuan, can set the value of 9 to 16 bits. Due to the larger value, the more common strings that can be used, the greater the compression ratio, so the preset value of 16 bits (bits) is generally used.

D decompress the compressed file

V list publication message

example:

Complicate Source.dat into source.dat.z, if Source.dat.z already exists, the content is overwritten by the compressed file.

Compress -f Source.dat

Complicate Source.dat into source.dat.z and prints the compression ratio.

-V and -f can be used together

Compress -vf source.dat will import the data after the compressed data is output. Dat.z can change the compressed file name.

Compress -c Source.dat> Target.dat.z

The larger the value of -b, the larger the compression ratio, the range is 9-16, and the preset value is 16.

Compress -b 12 Source.dat

Unfolding Source.dat.z into Source.dat. If the file already exists, the user presses Y to determine the coverage file, and the file will be automatically covered if the -df program is used. Since the system will automatically join .Z is an extended file name, Source.dat will automatically be treated as Source.dat.z.

Compress -d Source.dat

Compress -d source.dat.z

Name: LPD

Use permission: All users

How to use: LPD [-l] [#port]

LPD is a resident printing machine management, which manages local or distal printers based on / etc / printcap content. Each printer defined in / etc / printcap must have a corresponding directory in / var / lpd. In the directory, a copy of the CF starts in a directory indicates a printing work waiting to be sent to the appropriate device. This file is usually generated by the LPR.

LPR and LPD constitute a system that can work offline. When you use LPR, the printing machine does not need to be available immediately, and no existence. LPD automatically monitors the status of the printing machine. When the press is online, the file will be sent immediately. This has to wait for the previous work to complete the previous job.

parameter:

-l: Display some of the unlocked messages on the standard output.

#port: In general, LPD uses GetServByName to get the appropriate TCP / IP Port, you can use this parameter to force LPD to use the specified port.

example:

This program is usually performed at the beginning of the system from the program in /etc/rc.d.

Name LPQ

- Display the work usage of unfinished lists in the listing machine

LPQ [L] [P] [User]

Description

LPQ displays items that are not completed in the list of lists managed by the LPD.

example

Example 1. Display all work in the LP list machine

# lpq -pljPrank Owner Job Files Total Size1st Root 238 (Standard Input) 1428646 Bytes

related functions

LPR, LPC, LPD

Name: LPR

Use permission: All users

How to use: lpr [-pprinter]

During the data sent by the standard input to the printing machine, the printing machine management program LPD will be given to the appropriate program or device processing later. The LPR can be used to process the material to be sent to the local or distal host.

parameter:

-pprinter: Send the data to the specified printer Printer, the preset value is LP.

example:

Send www.c and kkk.c to the printing machine LP.

lpr-plp www.c kkk.c

Name: lprm

- Remove the usage by a work by the print machine

/ usr / bin / lprm [p] [file ...]

Description

The work that has not been completed will be placed in the printing machine, which can be used to cancel the work of the printing machine. Since each printer has a separate storage, you can use the -P command to set the printed machine you want to function. If there is no setting, the system preset press will be used.

This command checks if the user has enough permissions to delete the specified file. In general, only the owner of the file or the system administrator has this permission.

example

Remove LPRM -PPRINTER 1123 to Work in the printing machine HPPrinter

Working No. 1011 is removed from the preset printing machine

LPRM 1011

Name: fdformat

Use permission: All users

How to use: fdformat [-n] Device

Instructions for use :

Low-order formatting for the specified soft disc device. When using this instruction to format the floppy disk, it is best to specify the following device:

/ dev / fd0d360 disk machine A:, magnetic 360KB disk

/ DEV / FD0H1440 disk machine A:, magnetic disk is 1.4MB disk

/ DEV / FD1H1200 disk machine B:, magnetic disk is 1.2MB disk

If you use a device like / dev / fd0, if the disk inside is not a standard capacity, formatting may fail. In this case, the user can specify the necessary parameters first with the setFDPRM instruction.

parameter:

-N Close the confirmation function. This option closes the formatted confirmation step.

example:

FDFORMAT-N / DEV / FD0H1440

Format the magnetic disk of the disk machine A into a 1.4MB magnetic sheet. And the confirmation step is omitted.

Name: MFormat

Use permission: All users

Use mode:

MFORMAT [-T cylinders] [-h heads] [-l volume_label] [-f] [-i fsver-sion] [-S SIZECODE] [-2 Sectors_ON_TRACK_0] [-M Software_sector_size] [-A ] [-X] [-C] [-H hidden_sectors] [-r root_sector] [-b boot_sector] [-0 rate_on_track_0] [-A rate_on_other_tracks] [-1] [-k] Drive:

The DOS archive system is established on a magnetic sheet that has been made in low-order formatting. If you open the parameters of the USE_2M when compiling MTools, the partial parameters associated with the 2M format will work. Otherwise these parameters (like S, 2, 1, m) do not act.

parameter:

-T magnetic column (Synlider)

-H head (HEAD)

-S number of magnetic regions per magnetic

-l tag

-F The formatted magnetic disc is formatted to FAT32, but this parameter is still in the experiment.

-I Sets the version number in the FAT32. This is of course still in the experiment.

-S magnetic area size code, calculation mode for sector = 2 ^ (size code 7)

-C Magnetic bush (Cluster) of the magnetic area. If the given number causes the number of magnets that exceed the FAT table, MFORMAT will automatically amplify the number of magnetic regions.

-S

-M Software magnetic area size. This number is the magnetic area size returned by the system. Usually the same as the actual size.

-A If this parameter is added, MFormat generates a set of ATARI systems to this soft disc.

-X Format the flop to XDF format. Before use, you must use the XDFCOPY instruction to make a low-order formatting action.

-C Generates a disk image file (Disk Image) that can be installed with MS-DOS archive system. Of course, this parameter is meaningless to an entity disk machine.

-H hidden the number of magnetic regions. This is usually suitable for the split area of ​​the formatting the hard drive because there is a segmentation table in front of a divided area. This parameter is not tested, it can not be used.

-N disk serial number

The size of the -R root directory, the unit is the number of magnetic regions. This parameter is only valid for FAT12 and FAT16.

-B uses the specified file or the power-on magnetic area of ​​the device as the boot magnetic area of ​​this flap or division area. Of course, the hardware parameters are faded. -k Try to maintain the original boot magnetic area.

-0 Data transfer rate of the 0th rail

-A Data transfer rate outside the track

-2 use 2M format

-1 Do not use 2M format

example:

MFORMAT A:

This will use the preset value to format the disk in A: (already / DEV / FD0).

Name: MKDOSFS

Use permission: All users

How to use: MKDOSFS [-C | -L filename]

[-f number_of_fats]

[-F fat_size]

[-i volume_id]

[-M message_file]

[-n volume_name]

[-r root_dir_entry?]

[-s sector_per_cluster]

[-v]

DEVICE

[block_count]

Description: Establish a DOS archive system. Device means that you want to establish a device code for a DOS archive system. Like / dev / hda1, etc. Block_count is the number of blocks you want to configure. If block_count is not specified, the system automatically calculates the number of blocks that meet the size of the device.

parameter:

-c Create a file system before checking there is a bad track.

-l reads bad track records from the determined file.

-f Specifies the number of FAT, File Allocation Table. The preset value is 2. At present, Linux's FAT archive system does not support more than 2 FAT tables. Usually this doesn't need to be changed.

-F Specifies the size of the FAT table, usually 12 or 16 positions. The 12-bit group is usually used for the disks, and the 16-bit component group is used for the general hard disk division area, that is, the so-called FAT16 format. This value typically systematically selects the appropriate value itself. Using FAT16 on the disk usually does not take effect, it is also possible to use FAT12 on the hard disk.

-i Specifies the Volume ID. Generally, a number of four-bit tuples, like 2E203A47. If you don't give your system you will be generated.

-m When the user tries to boot with this magnetic or divided zone, the system will give the user a warning message to the user when there is no working system. This parameter is used to change this message. You can use the file to edit it, then specify this parameter, or use

-m -

This system will ask you to enter this text directly. It is important to note that the strings in the file should not exceed 418 words, including the unfolded jumper symbol (Tab) and the wrap symbol (the wrap symbol counts two characters under DOS!)

-n Specifies Volume Name, which is a disk label. Like the Format directive under the DOS, you will not give it. There is no preset value.

-r Specifies the maximum number of files under the root directory. The so-called number of files here includes the directory. The preset value is 112 or 224 on the floppy disc, 512 on the hard disk. Nothing, don't change this number.

-S Magnetic area of ​​each magnetic busner. Must be two times. But unless you know what you are doing, this value should not be gave.

-v provides additional messages

example:

MKDOSFS-N TESTER / DEV / FD0 format the disk in the A slot into a DOS format, and set the label to Tester

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