ubuntu:environment_variables
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| ubuntu:environment_variables [2019/12/15 20:53] – peter | ubuntu:environment_variables [2020/07/15 09:30] (current) – external edit 127.0.0.1 | ||
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| - | ===== Common Environment Variables ===== | ||
| - | |||
| - | ^Variable^Description^ | ||
| - | |PATH|This variable contains a colon (: | ||
| - | |USER|The username| | ||
| - | |HOME|Default path to the user's home directory| | ||
| - | |EDITOR|Path to the program which edits the content of files| | ||
| - | |UID|User' | ||
| - | |TERM|Default terminal emulator| | ||
| - | |SHELL|Shell being used by the user| | ||
| ---- | ---- | ||
| - | ===== Commands for Environment Variables ===== | + | ===== Commands for managing |
| Environment variables are case-sensitive and usually they are created in upper case. | Environment variables are case-sensitive and usually they are created in upper case. | ||
| ^Command^Description^ | ^Command^Description^ | ||
| - | |echo $VARIABLE|To display value of a variable| | + | |echo $VARIABLE|To display value of a variable.| |
| - | |printenv|Displays all or part of environment variables| | + | |printenv|Displays all or part of environment variables,| |
| |env|Displays all exported environment variables.| | |env|Displays all exported environment variables.| | ||
| - | |VARIABLE_NAME= variable_value|Create a new variable| | + | |VARIABLE_NAME= variable_value|Create a new variable.| |
| - | |set|Display the name and value of each shell variable| | + | |set|Display the name and value of each shell variable.| |
| - | |unset|Remove a variable| | + | |unset|Remove a variable.| |
| - | |export Variable=value|To set value of an environment variable| | + | |export Variable=value|To set value of an environment variable.| |
| ---- | ---- | ||
| - | ===== Commonly used variables | + | ===== Common Environment Variables |
| ^System Variable^Meaning^To View Variable Value Type^ | ^System Variable^Meaning^To View Variable Value Type^ | ||
| Line 45: | Line 34: | ||
| |HISTFILESIZE|The maximum number of lines contained in the history file.|echo $HISTFILESIZE| | |HISTFILESIZE|The maximum number of lines contained in the history file.|echo $HISTFILESIZE| | ||
| |HISTSIZE|The number of commands to remember in the command history. The default value is 500.|echo $HISTSIZE| | |HISTSIZE|The number of commands to remember in the command history. The default value is 500.|echo $HISTSIZE| | ||
| + | |USER|The username of the current user|echo $USER| | ||
| |HOME|The home directory of the current user.|echo $HOME| | |HOME|The home directory of the current user.|echo $HOME| | ||
| |IFS|The Internal Field Separator that is used for word splitting after expansion and to split lines into words with the read builtin command. The default value is < | |IFS|The Internal Field Separator that is used for word splitting after expansion and to split lines into words with the read builtin command. The default value is < | ||
| Line 52: | Line 42: | ||
| |TMOUT|The default timeout for the read builtin command. Also in an interactive shell, the value is interpreted as the number of seconds to wait for input after issuing the command. If not input provided it will logout user.|echo $TMOUT| | |TMOUT|The default timeout for the read builtin command. Also in an interactive shell, the value is interpreted as the number of seconds to wait for input after issuing the command. If not input provided it will logout user.|echo $TMOUT| | ||
| |TERM|Your login terminal type.|echo $TERM; export TERM=vt100| | |TERM|Your login terminal type.|echo $TERM; export TERM=vt100| | ||
| - | |SHELL|Set path to login shell.|echo $SHELL| | + | |SHELL|Path to login shell being used by the user.|echo $SHELL| |
| |DISPLAY|Set X display name|echo $DISPLAY; export DISPLAY=: | |DISPLAY|Set X display name|echo $DISPLAY; export DISPLAY=: | ||
| - | |EDITOR|Set name of default text editor.|export EDITOR=/ | + | |EDITOR|Path to the program which edits the content |
| + | |UID|User' | ||
ubuntu/environment_variables.1576443196.txt.gz · Last modified: 2020/07/15 09:30 (external edit)