10 Essential Linux Commands Every Developer Should Master

Linux is an open, free, and powerful operating system widely used for development and server environments, making mastery of its command‑line tools essential.

01 pgrep

The pgrep command lists process IDs matching a pattern, e.g.: $ pgrep -u hchen22441 22444 It is equivalent to:

ps -ef | egrep '^hchen' | awk '{print $2}'

02 pstree

pstree

displays the process hierarchy as a tree:

[hchen@RHELSVR5 ~]$ pstree
init-+-acpid
     |-auditd-+-python
     |        `-{auditd}
     |-automount---4*[{automount}]
     |-backup.sh---sleep
     ... (truncated for brevity)

03 bc

bc

provides high‑precision arithmetic. A sample script sqrt computes square roots:

#!/bin/bash
if [ $# -ne 1 ]
then
    echo 'Usage: sqrt number'
    exit 1
else
    echo -e "sqrt($1)
quit
" | bc -q -i
fi

Usage examples:

[hchen@RHELSVR5]$ ./sqrt 36
6
[hchen@RHELSVR5]$ ./sqrt 2.0000
1.4142
[hchen@RHELSVR5]$ ./sqrt 10.0000
3.1622

04 split

split

divides a large file into smaller pieces. Example:

[hchen@RHELSVR5 applebak]# split -b 50m largefile.tar.gz LF_

Resulting files (LF_aa, LF_ab, …) can be recombined with:

[hchen@RHELSVR5]# cat LF_* > largefile.tar.gz

05 nl

nl

numbers lines of a file, similar to cat but adds line numbers:

[hchen@RHELSVR5 include]# nl stdio.h | head -n 10
     1  /* Define ISO C stdio on top of C++ iostreams.
     2  Copyright (C) 1991,1994-2004,2005,2006 Free Software Foundation, Inc.
     3  This file is part of the GNU C Library.
     4  The GNU C Library is free software; you can redistribute it and/or
     5  modify it under the terms of the GNU Lesser General Public
     6  License as published by the Free Software Foundation; either
     7  version 2.1 of the License, or (at your option) any later version.
     8  The GNU C Library is distributed in the hope that it will be useful,

06 mkfifo

mkfifo

creates a named pipe (FIFO). Example:

[hchen@RHELSVR5 ~]# mkfifo /tmp/hchenpipe
[hchen@RHELSVR5 ~]# ls -l /tmp
prw-rw-r-- 1 hchen hchen 0 05-10 18:58 hchenpipe

Writing to the pipe blocks until another process reads from it: [hchen@RHELSVR5 ~]# ls -al > /tmp/hchenpipe Reading from the pipe releases the block:

[hchen@RHELSVR5 ~]# head /tmp/hchenpipe

07 ldd

ldd

lists the shared libraries required by an executable, e.g.:

[hchen@RHELSVR5 ~]# ldd /usr/bin/java
linux-gate.so.1 => (0x00cd9000)
libgij.so.7rh => /usr/lib/libgij.so.7rh (0x00ed3000)
... (other libraries omitted for brevity)

08 col

col

converts man pages to plain text. Example:

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

09 xmlwf

xmlwf

validates an XML file. Example workflow:

[hchen@RHELSVR5 ~]# curl 'https://coolshell.cn/?feed=rss2' > cocre.xml
[hchen@RHELSVR5 ~]# xmlwf cocre.xml
cocre.xml:13:23: mismatched tag

10 lsof

lsof

lists open files and the processes using them. Example showing listening services:

[root@RHELSVR5 ~]# lsof | grep TCP
httpd 548 apache 6u IPv6 14300972 TCP *:http (LISTEN)
sshd 1764 root 3u IPv6 4993 TCP *:ssh (LISTEN)
mysqld 10202 mysql 10u IPv4 73819697 TCP *:mysql (LISTEN)
...