Setting of Linux environment variable and save a place
Tuesday, March 03, 2009 by rain
? ? 1. HOME of indication environment variable
? ? $ Echo $HOME
? ? / Home/redbooks
? ? 2. Install a new environmental variable Hello
? ? $ Export HELLO="Hello! ? ? $ Export HELLO="Hello!!
? ? $ Echo $HELLO
? ? Hello!
? ? 3. Use Env command shows all environments are variable
? ? $ Env
? ? HOSTNAME=redbooks.safe.org
? ? PVM_RSH=/usr/bin/rsh
? ? SHELL=/bin/bash
? ? TERM=xterm
? ? HISTSIZE=1000
? ? . . .
? ? 4. Use Set commands the Shell that shows all this locality are defined is variable
? ? $ Set
? ? BASH=/bin/bash
? ? BASH_VERSINFO=([0]="2"[1]="05b"[2]="0"[3]="1"[4]="release"[5]="i386-redhat-linux-gnu" )
? ? BASH_VERSION='2.05b.0(1)-release'
? ? COLORS=/etc/DIR_COLORS.xterm
? ? COLUMNS=80
? ? DIRSTACK=()
? ? DISPLAY=:0.0
? ? . . .
? ? 5. Use Unset command will keep clear of the environment is variable
The value that ? ? Set can set variable of a certain environment.The value of cleared environment variable commands with Unset.If did not assign a value,Should change value of a quantity will be set to be NULL.Give typical examples is as follows:
? ? $ Export TEST="Test. . . .. # increases TEST of an environment variable
? ? $ Env | This command of Grep TEST # has an input,Prove environmental variable TEST had existed
? ? TEST=Test. . .
? ? $ Unset $TEST # deletes environmental variable TEST
? ? $ Env | This command of Grep TEST # was not outputted,Prove environmental variable TEST had existed
? ? 6. Use Readonly commands the setting is read-only and variable
If ? ? used Readonly jussive word,Variable can be not revised or kept clear of.Give typical examples is as follows:
? ? $ Export TEST="Test. . . .. # increases TEST of an environment variable
? ? $ Readonly TEST # sets environmental variable TEST for read-only
? ? $ Unset TEST # can discover this variable cannot be deleted
? ? - Bash: Unset: TEST: Cannot Unset: Readonly Variable
? ? $ TEST="New" # can discover this is variable also cannot be revised
? ? - Bash: TEST: Readonly Variable
The setting of variable of ? ? environment is located in / Etc/profile file
If ? ? needs to increase new environmental variable to be able to add subordinate travel
? ? Export Path=$path:/path1:/path2:/pahtN