Several common small commands for viewing logged-in users:
1, W : Displays the currently logged on user and what they are doing
[Email protected] usr]# W
10:02:06 up 2 days, 2:06, 1 user, Load average:0.00, 0.00, 0.00
USER TTY from [email protected] IDLE jcpu PCPU
Root pts/0 10.109.134.247 Mon09 0.00s 0.40s 0.15s W
2, WhoAmI display the current login system valid user name
[Email protected] usr]# WhoAmI
Root
3. Who shows which users are currently logged in
Who-h display the current user at the same time the header information
Who-r Display current system RunLevel
[Email protected] usr]# Who-r
Run Level 3 2016-10-24 07:55
[email protected] usr]# who
Root pts/0 2016-10-24 09:01 (10.109.134.247)
Who-h
[Email protected] usr]# who-h
Name Line time Note- h shows the current user displaying header information at the same time
Root pts/0 2016-10-24 09:01 (10.109.134.247)
User name terminal type logon time telnet display login IP
Terminal type:
Console: Consoles
Pty: Physical Terminal (VGA) General Pty Terminal Connection only one
tty#: Virtual Terminal ("the") Local connection for virtual machines
ttys#: Serial terminal #表示第几个串行终端连接
pts/#: Pseudo terminal #表示第几个伪终端登录
4, L a ST: display/var/log/wtmp file showing user login history and System restart history
- N #: Show information about recent # times
5, Lastb: /var/log/btmp file that displays user error login attempts
-N #: Displays information about recent # times
6, Lastlog: Displays the last successful login information for each user;
- u USERNAME: Display recent login information for a specific user
7. basename displays the filename of the path
Basename/etc/service
[Email protected] usr]# Basename/etc/service
Service
$: script path and name when executing script
8, mail: View the current user's mail pieces
Mail-s Specifying message headers
Cat/etc/fstab | Mail-s "Hello,root" root
Send the/etc/fstab file content as the message body to the root user.
[Email protected] usr]# Cat/etc/fstab | Mail-s "Hello,root" root
[[Email protected] usr]# mail
Heirloom Mail Version 12.4 7/29/08. Type? For help.
"/var/spool/mail/root": 1 message 1 new
>n 1 root Wed Oct 14:14 35/1681 "Hello,root"
& 1 1 indicates the message number, enter to view the contents of message 1
Message 1:
From [email protected] Wed Oct 26 14:14:46 2016
Return-path: <[email protected]>
X-original-to:root
TS 0 0
TMPFS/DEV/SHM TMPFS Defaults 0 0
Devpts/dev/pts devpts gid=5,mode=620 0 0
Sysfs/sys Sysfs Defaults 0 0
PROC/PROC proc Defaults 0 0
&q Enter Q to exit the mail system
Held 1 Message In/var/spool/mail/root
9, hostname: Display host name
Hostname Donggen indicates that the host name of the current host is changed to Donggen
[Email protected] usr]# hostname
Xuelinux
[Email protected] usr]# hostname Donggen
[Email protected] usr]# hostname
Donggen
If the host name of the current host is not www.magedu.com, change it to www.magedu.com
If the host name of the current host is localhost, change it to www.magedu.com
If the host name of the current host is empty, or (none), or localhost, change it to Linux
[-Z ' hostname '] | | [' hostname ' = = ' (none) '-o ' hostname ' = = ' localhost '] && hostname Linux
10. Sleep # hibernate # seconds
11. Generate Random Number command echo "random"
$RANDOM: 0-32768 Random numbers in this range
[Email protected] ~]# echo "$RANDOM"
4742
[Email protected] ~]# echo "$RANDOM"
19762
[Email protected] ~]# echo "$RANDOM"
12593
Random number generator: Entropy pool (random number of storage pools, random numbers inside may be emptied)
/dev/random:
/dev/urandom:
Command instance:
1, check the current system, Donggen users are logged in:
W.H.O. | grep "Donggen"
[email protected] usr]# who | grep "Donggen"
Donggen pts/1 2016-10-26 11:34 (10.109.134.247)
2, write a script, using random to generate 10 random numbers, and find the maximum and minimum value
#!/bin/bash
#program
# Take a random 10-digit maximum and minimum value
#history Donggen 2016-10-26-20:55
Declare-i max=0
Declare-i min=0
For I in {1..10}; Do
Myrandom= $RANDOM
[$I-eq 1] && min= $MYRANDOM
If [$I-le 9]; Then
Echo-n "$MYRANDOM,"
Else
echo "$MYRANDOM"
Fi
[$MYRANDOM-gt $MAX] && max= $MYRANDOM
[$MYRANDOM-lt $MIN] && min= $MYRANDOM
Done
echo "$MAX, $MIN"
This article is from the "Learn Linux history" blog, please be sure to keep this source http://woyaoxuelinux.blog.51cto.com/5663865/1866101
Linux commands: W, who, WhoAmI, last, Lastb, Lastlog, basename, mail, hostname