Shell variables, environment variable configuration files, pipe breaks

ENV View variable set also view variable content more powerful than env

[[email protected] ~]# echo $HOSTNAME See the name of the variable

Binbinlinux

[Email protected] ~]# a=1;b=2

[[email protected] ~]# echo $a $b can output a value of two variables

0 S

Variable names cannot begin with a number the name of the variable cannot be used by the name of the system command

[[email protected] ~]# c= ' ls/tmp/' for example this has a space special character with ' ' ' cause

[Email protected] ~]# echo $c

ls/tmp/

[[email protected] ~]# cyvim= ' which vim ' would like to have him automatically get the result of this command to add an anti-quote

[Email protected] ~]# echo $cyvim

/usr/bin/vim

[Email protected] ~]# a=1

[[email protected] ~]# c= "$a" is separated by double quotation marks or the default A is a variable name .

[Email protected] ~]# echo $c

112

[Email protected] ~]# echo $a

1

[[email protected] ~]# bash child shell

[[Email protected] ~]# exit child Shell

Exit

[[email protected] ~]# Export a=1 Global statement

[[email protected] ~]# bash into the child shell

[Email protected] ~]# echo $a

1

[[email protected] ~]# vim/etc/profile Add a custom variable to the configuration file

[Email protected] ~]# echo $c

1

[[email protected] ~]# unset c Cancel variable value unset

[Email protected] ~]# Vim/etc/profile

[[email protected] ~]# vim/etc/profile.d/path.sh defined path

#!/bin/bash

Export path= $PATH:/tmp/Global Declaration path= $PATH:/tmp/

~

Source/etc/profile immediate effect

[Email protected] ~]# echo $PATH you'll find a little more/tmp/.

/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/tmp/:/root/bin:/tmp/

[Email protected] ~]# echo $PATH

/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/tmp/:/root/bin:/tmp/

[[Email protected] ~]# Modify PATH

path=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin:/tmp/

[[email protected] ~]# Source/etc/profile effective

[[email protected] ~]# echo $PATH view

/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin:/tmp/:/tmp/

[Email protected] ~]# echo $PS 1

[\[email protected]\h \w]\$

[[email protected] ~]# ps1= ' [\[email protected]\h \w]\$ ' Modify PS1

[[email protected] ~]# ps1= ' [\[email protected]\h \w]\$ '

[[Email protected] ~] #cd/etc/init.d/

[[email protected]/etc/init.d] #PS1 = ' [\[email protected]\h \t\w]\$ '

[[email protected] 18:21:02/etc/init.d] #PS1 = ' [\[email protected]\h-\t\w]\$ '

[[email protected] 18:21:18/etc/init.d] #PS1 = ' [\[email protected]\h\w]\$ '

[[email protected]] #cd

[Email protected]~] #echo $PS 1

[\[email protected]\h\w]\$

vim/etc/profile.d/umask.sh Modify umask configuration file to 0023

Umask 0023

Then the Source/etc/profile declaration takes effect

Customizing profile environment variables for users themselves

Vim. Bash_profile definition

Vim. BASHRC Alias for user

[[email protected] ~]# ls *.txt wildcard * Can be multiple digits can be listed * below the number of digits *.txt

1.txt c.txt M.txt Z.txt

[email protected] ~]# ls?. Txt? Thought you could list the. txt

1.txt c.txt M.txt Z.txt

#号注释 comment does not take effect

\ de-Justification symbol

[email protected] ~]# ls #1. txt executes the LS command #号把后面注释了

Install.log M.txt

[[email protected] ~]# ls \ #1. txt you can get the # number off the back.

LS: Unable to access #1.txt: No file or directory

[[email protected] ~]# cat 1.txt |wc-l Throw the results of this command to the back of the day.

460

[[email protected] ~]# echo $PATH $ is a variable prefix

/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/tmp/:/data/bin:/root/bin

！ $ go to execute this command at a time

[email protected] ~]# ls 1.txt; LS P.txt write a line of two commands; separate the numbers.

1.txt

~ Indicates the user's home directory

[[email protected] ~]# ls ~ equivalent to ls/root/

Install.log M.txt

[[email protected] ~]# Sleep & & Throw a command backstage.

[1] 1701

[[email protected] ~]# jobs is running

[1]+ Running Sleep &

[[email protected] ~]# jobs

[1]+ done Sleep 10

[[Email protected] ~]# > redirect >> Chase-weighted redirect 2> error redirect 2>> error append redirect

[[email protected] ~]# Wc-l <1.txt < reverse redirect

460

[[email protected] ~]# ls [1-9a-za-z].txt brackets indicate range such as 1-9 can be all listed

1.txt 2.txt c.txt m.txt z.txt

This article is from the "11325852" blog, please be sure to keep this source http://11335852.blog.51cto.com/11325852/1982678

Shell variables, environment variable configuration files, pipe breaks