Shell Scripting

Here are some links for bash programming that you may find useful.

http://tips-linux.net/en/content/pro-bash-programming

http://tips-linux.net/en/content/expert-shell-scripting

http://tips-linux.net/en/content/beginning-linux-command-line

http://tips-linux.net/en/content/bash-pocket-reference

http://tips-linux.net/en/content/linux-command-line-and-shell-scripting-bible

Related articles

• Linux – Learning the Shell (edugeek.net)
• 10 Useful Tools, Websites And Tricks to Help You Master Linux Command (maketecheasier.com)
• lf-submit.sh – Bash mplayer Last.fm scrobbler (yjl.im)
• Linux command line tricks you need to know: IO redirection and piping (interstellr.com)
• imabonehead: Houcem HACHICHA’s Blog: My top ten shell/bash tricks! (houcemhachicha.blogspot.com)

Bash Script Beautifier

Today I was working on a bash script written by someone else. And the script was maintained since long and had actually become quite big and there was no indentation followed. So, you can understand how difficult it was to understand the script. So, I set my foot forth to first find a beautifier for the bash script before I fixed it and my search ended here.

intercept stdout/stderr of another process or disowned process

The command is definately going to save your day if you have disowned the process by mistake. Only uses strace so might as well work on Solaris also, though not tried it.

intercept stdout/stderr of another process or disowned process

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      strace -e write=1,2 -p $PID 2>&1 | sed -un "/^ |/p" | sed -ue "s/^.{9 }(.{50}).+/1/g" -e 's/ //g' | xxd -r -p
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Useful to recover a output(stdout and stderr) “disown”ed or “nohup“ep process of other instance of ssh.

Broadcast your shell thru port 5000

Broadcast your shell thru port 5000

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      mkfifo /tmp/fifo;(nc -q0 -l 5000 < /tmp/fifo &);script -f /tmp/fifo
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run

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      nc yourip 5000
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elsewhere will produce an exact same mirror of your shell. This is handy when you want to show someone else some amazing stuff in your shell without giving them control over it.

Screen enable/disable logging in all windows

If you use screen command a lot then this is something that you will like 🙂

Screen enable/disable loggin in all windows

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      bindkey ^l at "#" log on<br /> <br /> bindkey ^o at "#" log off
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The command when added in screenrc enables logging all open windows by using the C-l (control-l key combination) and disable by C-o . The lines need to be added in separate lines .

function for copy files with progress bar (using pv – pipe viewer)

function for copy files with progress bar (using pv – pipe viewer)

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      &nbsp;cp_p() { if [ `echo "$2" | grep ".*/$"` ]; then pv "$1" > "$2""$1"; else pv "$1" > "$2"/"$1"; fi; }
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dont have to type new file name (it copy file under same name) and dont have to use ‘/’ in the end of destination folder (but you can if u want, its idiot proof)

Print all environment variables, including hidden ones

Print all environment variables, including hidden ones

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      for _a in {A..Z} {a..z};do _z=${!${_a}*};for _i in `eval echo "${_z}"`;do echo -e "$_i: ${!_i}";done;done|cat -Tsv
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This uses some tricks I found while reading the bash man page to enumerate and display all the current environment variables, including those not listed by the ‘env‘ command which according to the bash docs are more for internal use by BASH. The main trick is the way bash will list all environment variable names when performing expansion on ${!A*}. Then the eval builtin makes it work in a loop.