Execute a command before display the bash prompt

PROMPT_COMMAND=command
For example, if you are the type who type ls very often, then PROMPT_COMMAND=ls will ls after every command you issue.

1
By: haivu
2009-10-15 06:01:18

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  • I don't know why anyone would use this, I was just messing around tonight and managed to start bash without using any letters and thought I would share. It's pretty simple, first it tries to execute "-" redirecting stderr to stdout which prints the error "bash: -: command not found" to standard output, then I try to execute "bash: -: command not found" which produces the output "bash: bash: -: command not found: command not found". lastly, (on the other side of the semicolon) I use the underscore environment variable which refers to the last command run ("bash: -: command not found") and take out everything after the first ":" character using brace expressions and your left with "bash" Show Sample Output


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    "$(- 2>&1)";${_%%:*}
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What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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