10个 Linux 命令，让你的操作更有效率

$ pgrep -u hchen2244122444

这个命令相当于：

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

02 pstree

这个命令可以以树形的方式列出进程。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

这个命令主要是做一个精度比较高的数学运算的。比如开平方根等。下面是一个我们利用bc命令写的一个脚本（文件名：sqrt）

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

于是，我们可以这样使用这个脚本进行平方根运算：

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

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简单的合并就行了，如：

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

05 nl

nl命令其它和cat命令很像，只不过它会打上行号。如下所示：

[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

[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

我们在另一个命令窗口中读取这个管道中的信息：（其会导致上一个命令返回）

[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

这个命令可以知道你的一个可执行文件所使用了动态链接库。如：

[hchen@RHELSVR5 ~]# ldd /usr/bin/java        linux-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

这个命令可以让你把man文件转成纯文本文件。如下示例：

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

09 xmlwf

这个命令可以让你检查一下一个XML文档是否是所有的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  Current                                 Dload  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

可以列出打开了的文件。

[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)

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