Bash Script Beautifier

2010-12-23 1 min read Bash Learning Linux

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

2010-11-23 1 min read Bash Fedora Linux

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

2010-11-20 1 min read Bash Fedora Linux

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.

Print all environment variables, including hidden ones

2010-11-09 2 min read Bash Fedora Linux

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.

bash script to run a command and take screenshot in every loop.

2010-09-24 2 min read Bash Fedora Learning Linux

Couple of days back, I had posted a command to display a stop timer with bash and echo. There I had also put the following gif file:

Here the tricky part was to capture the jpg’s to create the gif file.

Preparation:

Rename the terminal to aka – amit-capture

Execute the command once with the import command and check the output and jpg’s
Continue reading

bash – echo command with option to display the output on the same line.

2010-09-21 2 min read Bash Fedora Learning Linux

Here is a nice little trick to display the output in the same line :

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      &nbsp;<span class="kw3">echo</span> <span class="re5">-ne</span> <span class="st0">"output\<span class="es1">\r</span>"</span>
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The trick here is simple, first we disable the <a class="zem_slink" title="Newline" rel="wikipedia" href="http://en.wikipedia.org/wiki/Newline">newline printed by <a class="zem_slink" title="Echo (command)" rel="wikipedia" href="http://en.wikipedia.org/wiki/Echo_%28command%29">echo command with the ”-n” option and then we enable the interpretation of the <a class="zem_slink" title="Backslash" rel="wikipedia" href="http://en.wikipedia.org/wiki/Backslash">backslash characters with the ”-e” option. As the ”\r” is used as <a class="zem_slink" title="Carriage return" rel="wikipedia" href="http://en.wikipedia.org/wiki/Carriage_return">carriage return which brings you to the start of the line without the newline (like in <a class="zem_slink" title="Typewriter" rel="wikipedia" href="http://en.wikipedia.org/wiki/Typewriter">typewriter), we will use the same to get the desired effect. So, if you wanted a stopwatch for a 100 seconds on the console then this simple bash <a class="zem_slink" title="For loop" rel="wikipedia" href="http://en.wikipedia.org/wiki/For_loop">for loop would do the same:

Handy one-liners for SED

2010-09-14 0 min read Bash Linux

$\"A$: Image via Wikipedia

Here are some links to sed one liners, pretty useful if you want to use the power of sed.

<a href="http://www.freearchive.org/o/dd1ebea77f64bdef5982d50e868990202b0bf6f21b42e26ebb0ab1011d6ce546">http://www.freearchive.org/o/dd1ebea77f64bdef5982d50e868990202b0bf6f21b42e26ebb0ab1011d6ce546

<a href="http://www.unixguide.net/unix/sedoneliner.shtml">http://www.unixguide.net/unix/sedoneliner.shtml
<a href="http://sed.sourceforge.net/sed1line.txt">http://sed.sourceforge.net/sed1line.txt <a href="http://www.thegeekstuff.com/2010/06/bash-array-tutorial/">

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