10個 Linux 命令，讓你的操作更有效率
01 pgrep
pgrep名字前有個p，我們可以猜到這和進程相關，又是grep，當然這是進程相關的grep命令。不過，這個命令主要是用來列舉進程ID的。如：
$ pgrep -u hchen2244122444這個命令相當于：
ps -ef | egrep '^hchen' | awk '{print $2}'02 pstree
這個命令可以以樹形的方式列出進程。如下所示：
[hchen@RHELSVR5 ~]$ pstreeinit-+-acpid|-auditd-+-python| `-{auditd}|-automount---4*[{automount}]|-backup.sh---sleep|-dbus-daemon|-events/0|-events/1|-hald---hald-runner---hald-addon-acpi|-httpd---10*[httpd]|-irqbalance|-khelper|-klogd|-ksoftirqd/0|-ksoftirqd/1|-kthread-+-aio/0| |-aio/1| |-ata/0| |-ata/1| |-ata_aux| |-cqueue/0| |-cqueue/1| |-kacpid| |-kauditd| |-kblockd/0| |-kblockd/1| |-kedac| |-khubd| |-6*[kjournald]| |-kmirrord| |-kpsmoused| |-kseriod| |-kswapd0| |-2*[pdflush]| |-scsi_eh_0| |-scsi_eh_1| |-xenbus| `-xenwatch|-migration/0|-migration/1|-6*[mingetty]|-3*[multilog]|-mysqld_safe---mysqld---9*[{mysqld}]|-smartd|-sshd---sshd---sshd---bash---pstree|-svscanboot---svscan-+-3*[supervise---run]| |-supervise---qmail-send-+-qmail-clean| | |-qmail-lspawn| | `-qmail-rspawn| `-2*[supervise---tcpserver]|-syslogd|-udevd|-watchdog/0|-watchdog/1-xinetd
03 bc
這個命令主要是做一個精度比較高的數學運算的。比如開平方根等。下面是一個我們利用bc命令寫的一個腳本（文件名：sqrt）
#!/bin/bashif [ $# -ne 1 ]thenecho 'Usage: sqrt number'exit 1else???? echo -e "sqrt($1)\nquit\n" | bc -q -ifi
于是，我們可以這樣使用這個腳本進行平方根運算：
[hchen@RHELSVR5]$ ./sqrt 366[hchen@RHELSVR5]$ ./sqrt 2.00001.4142[hchen@RHELSVR5]$ ./sqrt 10.00003.1622
04 split
[hchen@RHELSVR5 applebak]# ls -l largefile.tar.gz-rw-r--r-- 1 hchen hchen 436774774 04-17 02:00 largefile.tar.gz[hchen@RHELSVR5 applebak]# split -b 50m largefile.tar.gz LF_[hchen@RHELSVR5]# ls -l LF_*-rw-r--r-- 1 hchen hchen 52428800 05-10 18:34 LF_aa-rw-r--r-- 1 hchen hchen 52428800 05-10 18:34 LF_ab-rw-r--r-- 1 hchen hchen 52428800 05-10 18:34 LF_ac-rw-r--r-- 1 hchen hchen 52428800 05-10 18:34 LF_ad-rw-r--r-- 1 hchen hchen 52428800 05-10 18:34 LF_ae-rw-r--r-- 1 hchen hchen 52428800 05-10 18:35 LF_af-rw-r--r-- 1 hchen hchen 52428800 05-10 18:35 LF_ag-rw-r--r-- 1 hchen hchen 52428800 05-10 18:35 LF_ah-rw-r--r-- 1 hchen hchen 17344374 05-10 18:35 LF_ai
文件合并只需要使用簡單的合并就行了，如：
[hchen@RHELSVR5]# cat LF_* >largefile.tar.gz05 nl
nl命令其它和cat命令很像，只不過它會打上行號。如下所示：
[hchen@RHELSVR5 include]# nl stdio.h | head -n 101 /* 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/or5 modify it under the terms of the GNU Lesser General Public6 License as published by the Free Software Foundation; either7 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
[hchen@RHELSVR5 ~]# mkfifo /tmp/hchenpipe[hchen@RHELSVR5 ~]# ls -l /tmpprw-rw-r-- 1 hchen hchen 0 05-10 18:58 hchenpipe
[hchen@RHELSVR5 ~]# ls -al > /tmp/hchenpipe我們在另一個命令窗口中讀取這個管道中的信息：（其會導致上一個命令返回）
[hchen@RHELSVR5 ~]# head /tmp/hchenpipedrwx------ 8 hchen hchen 4096 05-10 18:27 .drwxr-xr-x 7 root root 4096 03-05 00:06 ..drwxr-xr-x 3 hchen hchen 4096 03-01 18:13 backup-rw------- 1 hchen hchen 721 05-05 22:12 .bash_history-rw-r--r-- 1 hchen hchen 24 02-28 22:20 .bash_logout-rw-r--r-- 1 hchen hchen 176 02-28 22:20 .bash_profile-rw-r--r-- 1 hchen hchen 124 02-28 22:20 .bashrc-rw-r--r-- 1 root root 14002 03-07 00:29 index.htm-rw-r--r-- 1 hchen hchen 31465 03-01 23:48 index.php
07 ldd
這個命令可以知道你的一個可執行文件所使用了動態鏈接庫。如：
[hchen@RHELSVR5 ~]# ldd /usr/bin/javalinux-gate.so.1 => (0x00cd9000)libgij.so.7rh => /usr/lib/libgij.so.7rh (0x00ed3000)libgcj.so.7rh => /usr/lib/libgcj.so.7rh (0x00ed6000)libpthread.so.0 => /lib/i686/nosegneg/libpthread.so.0 (0x00110000)librt.so.1 => /lib/i686/nosegneg/librt.so.1 (0x009c8000)libdl.so.2 => /lib/libdl.so.2 (0x008b5000)libz.so.1 => /usr/lib/libz.so.1 (0x00bee000)libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x00aa7000)libc.so.6 => /lib/i686/nosegneg/libc.so.6 (0x0022f000)libm.so.6 => /lib/i686/nosegneg/libm.so.6 (0x00127000)/lib/ld-linux.so.2 (0x00214000)
08 col
這個命令可以讓你把man文件轉成純文本文件。如下示例：
# PAGER=cat# man less | col -b > less.txt09 xmlwf
這個命令可以讓你檢查一下一個XML文檔是否是所有的tag都是正常的。如：
[hchen@RHELSVR5 ~]# curl 'https://coolshell.cn/?feed=rss2' > cocre.xml% Total % Received % Xferd Average Speed Time Time Time CurrentDload Upload Total Spent Left Speed100?64882????0?64882????0?????0??86455??????0?--:--:--?--:--:--?--:--:--?2073k[hchen@RHELSVR5 ~]# xmlwf cocre.xml[hchen@RHELSVR5 ~]# perl -i -pe 's@<link>@<br>@g' cocre.xml[hchen@RHELSVR5 ~]# xmlwf cocre.xmlcocre.xml:13:23: mismatched tag
10 lsof
可以列出打開了的文件。
[root@RHELSVR5 ~]# lsof | grep TCPhttpd 548 apache 4u IPv6 14300967 TCP *:http (LISTEN)httpd 548 apache 6u IPv6 14300972 TCP *:https (LISTEN)httpd 561 apache 4u IPv6 14300967 TCP *:http (LISTEN)httpd 561 apache 6u IPv6 14300972 TCP *:https (LISTEN)sshd 1764 root 3u IPv6 4993 TCP *:ssh (LISTEN)tcpserver 8965 root 3u IPv4 153795500 TCP *:pop3 (LISTEN)mysqld 10202 mysql 10u IPv4 73819697 TCP *:mysql (LISTEN)sshd 10735 root 3u IPv6 160731956 TCP 210.51.0.232:ssh->123.117.239.68:31810 (ESTABLISHED)sshd 10767 hchen 3u IPv6 160731956 TCP 210.51.0.232:ssh->123.117.239.68:31810 (ESTABLISHED)vsftpd 11095 root 3u IPv4 152157957 TCP *:ftp (LISTEN)
來源：公眾號老九課堂。