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This article mainly introduces the example analysis of bash, sh,. / and source in shell, which is very detailed and has certain reference value. Friends who are interested must read it!

Sh and bash

/ bin/sh in the GNU/Linux operating system is originally a symbolic link to bash (Bourne-Again Shell), but because bash is too complex, someone migrates bash from NetBSD to Linux and renames it to dash (Debian Almquist Shell), and it is recommended to point / bin/sh to it for faster script execution. Dash Shell is much smaller than Bash Shell and meets the POSIX standard.

1. UbuntuLinux localhost 4.4.0-105-generic # 128-Ubuntu SMP Thu Dec 14 12:42:11 UTC 2017 x86 "64 GNU/Linuxxhx@localhost:~$ ls-la / bin/shlrwxrwxrwx 1 root root 4 Aug 17 2017 / bin/sh-> dash2. Centos [root @ xuhx-02 bin] # uname-aLinux xuhx-02 3.10.0-957.21.3.el7.x86_64 # 1 SMP Tue Jun 18 16:35:19 UTC 2019 x86'64 GNU/ Linux [root @ xuhx-02 bin] # ls-la shlrwxrwxrwx. 1 root root 4 June 25 16:52 sh-> bash

Sh/bash and source

Sh/bash opens the child shel and runs in the child shell. The environment variables set in the child shell will not affect the parent shell.

Source runs in the current shell, so after modifying the environment variables, you need to run source / etc/profile to make it effective instead of using the sh/bash command; source =.

. / requires r and x permissions on the executed script

[root@xuhx-02 ~] # sh t.shanaconda-ks.cfg hello n2n newdir1 pytho.py rpmbuild sort test.sh t.sh ttttt.sh [root @ xuhx-02 ~] # bash t.shanaconda-ks.cfg hello n2n newdir1 pytho.py rpmbuild sort test.sh t.sh ttttt.sh [root @ xuhx-02 ~] #. / t.sh-bash:. / t.sh: insufficient permissions [root@xuhx-02 ~] # source t.shanaconda-ks.cfg hello n2n newdir1 pytho .py rpmbuild sort test.sh t.sh ttttt.sh [root @ xuhx-02 ~] #. T.sh anaconda-ks.cfg hello n2n newdir1 pytho.py rpmbuild sort test.sh t.sh ttttt.sh and above are all the contents of this article entitled "sample Analysis of bash, sh,. /, source in shell". Thank you for reading! Hope to share the content to help you, more related knowledge, welcome to follow the industry information channel!

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