PROMPT_COMMANDīash shell executes the content of the PROMPT_COMMAND just before displaying the PS1 variable. While tracing the output using set -x] 5.
COMMANDER ONE PRO DIFFERENCE PS4
The PS4 defined below in the ps4.sh has the following two codes: Shell script and output WITHOUT PS4: ~> cat ps4.sh The PS4 shell variable defines the prompt that gets displayed, when you execute a shell script in debug mode as shown below. PS4 – Used by “set -x” to prefix tracing output Shell script and output WITH PS3: ~> cat ps3.sh Shell script and output WITHOUT PS3: ~> cat ps3.sh
COMMANDER ONE PRO DIFFERENCE PS3
You can define a custom prompt for the select loop inside a shell script, using the PS3 environment variable, as explained below. PS3 – Prompt used by “select” inside shell script What is your preference? Do you like breaking up long commands into multiple lines?ģ. I have also seen others who don’t like to break-up long commands. I found it very helpful and easy to read, when I break my long commands into multiple lines using \. [Note: This uses the default ">" for continuation ~> export PS2="continue-> ~> myisamchk -silent -force -fast -update-state \Ĭontinue-> -key_buffer_size=512M -sort_buffer_size=512M \Ĭontinue-> -read_buffer_size=4M -write_buffer_size=4M \ > -read_buffer_size=4M -write_buffer_size=4M \ ~> myisamchk -silent -force -fast -update-state \ Let us change this default behavior to display “continue->” by using PS2 environment variable as shown below. The default interactive prompt for a multi-line command is “> “. PS2 – Continuation interactive promptĪ very long unix command can be broken down to multiple line by giving \ at the end of the line. In the next post, I’ll write about several practical examples of PS1 usage in detail. Make this setting permanent by adding export \w> ” to either. Personally, I prefer a space at the end of the prompt for better readability. Note that there is a space at the end in the value of PS1.Please note that when you are in the home directory, this will display only ~ as shown above
COMMANDER ONE PRO DIFFERENCE FULL
\w – Full pathname of current directory.bash-3.2$ export \w> ~> cd /etc/mail>įollowing PS1 codes are used in this example: Let us change this default behavior to display the username, hostname and current working directory name as shown below. In the following example, the default PS1 was “\s-\v\$”, which displays the shell name and the version number. The default interactive prompt on your Linux can be modified as shown below to something useful and informative. This article will give you a jumpstart on the Linux command prompt environment variables using simple examples. Your interaction with Linux Bash shell will become very pleasant, if you use PS1, PS2, PS3, PS4, and PROMPT_COMMAND effectively.
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