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This article mainly shows you "what are the less used Linux commands", the content is simple and easy to understand, and the organization is clear. I hope it can help you solve your doubts. Let Xiaobian lead you to study and learn "what are the less used Linux commands" this article.

1. pgrep, substitute:

# ps -ef | egrep '^root ' | awk '{print $2}'1234520213839...

You can also do this:

# pgrep -u root1234520213839...

2. pstree, which lists processes in tree format, is very useful when there is webSphere or heavy task application.

# pstreeinit-+-acpid|-atd|-crond|-cups-config-dae|-cupsd|-dbus-daemon-1|-dhclient|-events/0-+-aio/0| |-kacpid| |-kauditd| |-kblockd/0| |-khelper| |-kmirrord| `-2*[pdflush]|-gpm|-hald|-khubd|-2*[kjournald]|-klogd|-kseriod|-ksoftirqd/0|-kswapd0|-login---bash|-5*[mingetty]|-portmap|-rpc.idmapd|-rpc.statd|-2*[sendmail]|-smartd|-sshd---sshd---bash---pstree|-syslogd|-udevd|-vsftpd|-xfs`-xinetd

bc is an arbitrary precision calculator language that can perform square root operations with Shell scripts, expr does not support square roots.

# ./ sqrtUsage: sqrt number# ./ sqrt 648# ./ sqrt 132112363# ./ sqrt 132112132136347Here is the script:# cat sqrt#!/ bin/bashif [ $# -ne 1 ]thenecho 'Usage: sqrt number'exit 1elseecho -e "sqrt($1)\nquit\n" | bc -q -ifi

Do you need to split a large file into smaller pieces?

Split is your command, and here's how to split a 250MB file into 2 MB chunks, all starting with LF_prefix.

# ls -lh largefile-rw-r--r-- 1 root root 251M Feb 19 10:27 largefile# split -b 2m largefile LF_# ls -lh LF_* | head -n 5-rw-r--r-- 1 root root 2.0M Feb 19 10:29 LF_aa-rw-r--r-- 1 root root 2.0M Feb 19 10:29 LF_ab-rw-r--r-- 1 root root 2.0M Feb 19 10:29 LF_ac-rw-r--r-- 1 root root 2.0M Feb 19 10:29 LF_ad-rw-r--r-- 1 root root 2.0M Feb 19 10:29 LF_ae# ls -lh LF_* | wc -l126

5, nl digital line, before the discovery of nl, has been implemented with scripts.

# head wireless.h/** This file define a set of standard wireless extensions** Version : 20 17.2.06** Authors : Jean Tourrilhes - HPL* Copyright (c) 1997-2006 Jean Tourrilhes, All Rights Reserved.*/# ifndef _LINUX_WIRELESS_H# nl wireless.h | head1 /*2 * This file define a set of standard wireless extensions3 *4 * Version : 20 17.2.065 *6 * Authors : Jean Tourrilhes - HPL7 * Copyright (c) 1997-2006 Jean Tourrilhes, All Rights Reserved.8 */9 #ifndef _LINUX_WIRELESS_H

Mkfifo is the coolest one, you must know how to create pipes to transport grep results to LESS, maybe even perl.

But do you know how to make 2 commands communicate through 1 named pipe? Look at the image below, create the pipe and start writing to it.

Then read it:

7, ldd, want to know which Linux thread library java links to?

# ldd /usr/java/jre1.5.0_11/bin/javalibpthread.so.0 => /lib/tls/libpthread.so.0 (0x00bd4000)libdl.so.2 => /lib/libdl.so.2 (0x00b87000)libc.so.6 => /lib/tls/libc.so.6 (0x00a5a000)/lib/ld-linux.so.2 (0x00a3c000)

8, col, want to save the help page as plain text?

# PAGER=cat# man less | col -b > less.txt

9, xmlwf, need to know whether an XML document or configuration file is reasonable?

# curl -s 'http://bashcurescancer.com' > bcc.html# xmlwf bcc.html# perl -i -pe 's@@@g' bcc.html# xmlwf bcc.htmlbcc.html:104:2: mismatched tag

10, lsof lists open files, you can use it to do a lot of cool things, such as finding which interface is open?

# lsof | grep TCPportmap 2587 rpc 4u IPv4 5544 TCP *:sunrpc (LISTEN)rpc.statd 2606 root 6u IPv4 5585 TCP *:668 (LISTEN)sshd 2788 root 3u IPv6 5991 TCP *:ssh (LISTEN)sendmail 2843 root 4u IPv4 6160 TCP badhd:smtp (LISTEN)vsftpd 9337 root 3u IPv4 34949 TCP *:ftp (LISTEN)cupsd 16459 root 0u IPv4 41061 TCP badhd:ipp (LISTEN)sshd 16892 root 3u IPv6 61003 TCP badhd.mshome.net:ssh->kontiki.mshome.net:4661 (ESTABLISHED)Note: OpenBSD 101 pointed out that "lsof -i TCP" a better way to obtain this same information. Thanks! Or find the number of open files a user has. Very important for running big applications like Oracle, DB2, or WebSphere:# lsof | grep ' root ' | awk '{print $NF}' | sort | uniq | wc -l179

Hint, anonymous commenter pointed out that "sort-u" should be used instead of sort| uniq, I forgot-u flag, thank you!

The above is "What are the less used Linux commands" all the content of this article, thank you for reading! I believe that everyone has a certain understanding, hope to share the content to help everyone, if you still want to learn more knowledge, welcome to pay attention to the industry information channel!

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