A few unknown but very useful commands for the shell to share the _linux shell

Having recently been using the Linux operating system and being familiar with some simple commands, I'll introduce you to some of the less-known but very useful commands:

1.mtr command to view the direct network connection of a MTR running host and a Web site, as follows

MTR google.com

Show the content

Copy Code code as follows:

My traceroute [v0.75]
Localhost.localdomain (0.0.0.0) Sun May 18 19:32:36 2014
Keys:help Display Mode Restart Statistics Order of fields quit
Packets pings
Host loss% Snt last AVG best Wrst StDev
1.103.31.240.129 0% 42 0.5 0.5 0.5 0.6 0.0
2.118.126.0.9 0% 42 0.3 0.3 0.2 0.4 0.0
3.210.245.144.37 0% 42 2.9 3.6 2.9 22.1 3.0
4.113.10.231.125 0% 42 3.1 3.8 2.7 40.2 5.8
5. irb9.10g-tc2.wpc.nwtgigalink.com 0% 42 2.9 3.1 2.9 5.1 0.4
6. ae2.10g-pp2.wpc.nwtgigalink.com 0% 42 3.2 3.0 2.9 3.2 0.1
7. Google3-10g.hkix.net 0% 42 4.6 4.5 4.3 4.6 0.1
8.209.85.248.62 0% 42 5.0 5.3 4.8 13.7 1.6
9.209.85.241.171 0% 42 5.3 5.2 5.1 5.7 0.1
Hkg03s16-in-f8.1e100.net 0% 41 4.8 4.9 4.7 5.0 0.1

2.nl command, add the line number to the text you are viewing, as follows

Cat A.log
Aa

NL A.log
1 AA
3.SHUF command to randomly select rows or files from a file or a folder

Copy Code code as follows:

[Root@localhost mwq]# ls | Shuf-n1
A.log
[Root@localhost mwq]# ls | Shuf-n1
A.log
[Root@localhost mwq]# ls | Shuf-n1
A.log
[Root@localhost mwq]# ls | Shuf-n1
20140512.sql
[Root@localhost mwq]# ls | Shuf-n1
20140512.sql
[Root@localhost mwq]# ls | Shuf-n1
A.log
[Root@localhost mwq]# Vim A.log
[Root@localhost mwq]# Cat A.log | Shuf-n1
Aa
[Root@localhost mwq]# Cat A.log | Shuf-n1
Dd
[Root@localhost mwq]# Cat A.log | Shuf-n1
Aa
[Root@localhost mwq]# Cat A.log | Shuf-n1
Ff

Of course you can also change parameters such as Cat A.log | Shuf-n2 gets two lines of content.

4.last command to view the last logged-on or logged out user

Copy Code code as follows:

Root PTS/4 xxxxxxxxxxx Sun may 19:12 still logged in
Root PTS/4 xxxxxxxxxxx Fri May 16 09:39-15:17 (05:38)
Root PTS/4 xxxxxxxxxxx Wed May 14 17:13-18:01 (00:48)
Root PTS/4 xxxxxxxxxxx Mon May 12 10:50-13:38 (02:47)
Root PTS/4 xxxxxxxxxxx Mon May 12 10:48-10:50 (00:02)
Root PTS/1 xxxxxxxxxxx Fri May 9 11:58 still logged in

5.pstree Displays the current process node in the structure of the tree

Init─┬─abrt-dump-oops
 ├─ABRTD
 ├─acpid
 ├─atd
 ├─AUDITD───{AUDITD}
 ├─avahi-daemon───avahi-daemon
 ├─console-kit-dae───63*[{console-kit-da}]
 ├─crond
 ├─dbus-daemon───{dbus-daemon}
 ├─HALD───HALD-RUNNER─┬─HALD-ADDON-ACPI
 │     └─hald-addon-inpu
 ├─irqbalance
 ├─java───330*[{java}]
 ├─master───qmgr
 ├─6*[mingetty]
 ├─mysqld_safe───mysqld───11*[{mysqld}]
 ├─RHSMCERTD───RHSMCERTD
 ├─RSYSLOGD───3*[{RSYSLOGD}]
 ├─sshd─┬─4*[sshd───bash]
 │ └─sshd───bash───pstree
 ├─stap-serverd
 ├─udevd───2*[udevd]
 └─vsftpd
OK, so much for today, and later on ....