Define shell variable HISTIGNORE so that comments (lines starting with #) appear in shell history

export HISTIGNORE=' cd "`*: PROMPT_COMMAND=?*?'
I was surprised to find that with RedHat bash, I could not find any comment lines (begining with #) in my bash shell history. Surprised because in Mageia Linux this works. It turns out that RedHat's bash will keep comment lines if in my .bashrc, I define: export HISTIGNORE=' cd "`*: PROMPT_COMMAND=?*?' Why have comment lines in shell history? It's a handy and convenient way to make proto-commands (to be completed later) and for storing brief text data that is searchable in shell history.
Sample Output
$ export HISTIGNORE=' cd "`*: PROMPT_COMMAND=?*?' ; exec bash
$ # store some text here
$ history | tail -3
 1000  export HISTIGNORE=' cd "`*: PROMPT_COMMAND=?*?' ; exec bash
 1001  # store some text here
 1002  history | tail -3

1
By: mpb
2011-10-18 19:58:39

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  • Shows a file without comments (at least those starting by #) - removes empty lines - removes lines starting by # or "some spaces/tabs then #'" Useful when you want to quickly see what you have to customize on a freshly installed application without reading the comments that sometimes are a full 1000 lines documentation :) While posting, I saw this http://www.commandlinefu.com/commands/view/1041/display-contents-of-a-file-wo-any-comments-or-blank-lines But it's dirty and incomplete, to my mind My original goal was to remove lines like "\t*#" but I can't figure out how to do a egrep '\t' on a command-line. Two workarounds if needed: egrep -v 'press control + V then TAB then #' /your/file or egrep -v -f some_file /your/file #where some_file contains what you want to exclude, example a really inserted TAB


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    egrep -v "^$|^[[:space:]]*#" /etc/some/file
    michauko · 2009-05-12 07:14:48 4

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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