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, once again
-l: List all specified (users can also use ATQ directly without 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 1213 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 22 23 24 25 26 17 18 19 20 21 22 23
29 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 Monday is the first day of week, showing this month's calendar.
[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 78 100 101 102 103 104 105 106
79 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 29 29 297 298 299 300 301 302268 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 SetENV Visual Joe)
-r: Delete the current schedule
-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 minutes, CC is The first two digits in the year, 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]
Speaking: The use of the Time instruction is to measure the time and system resources such as the measurement of 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 the total amount of memory occupied by the KBK execution program (STACK DATA TEXT), and the unit 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
"Finger [Back]
Name: finger
Use permission: 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
It is. PLAN, .Project and .Forward are the information in the files such as .ble, .project, and .forward in his Home Directory. 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
