Commands using cat (514)

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Replaces a color in a PDF document, useful for removing a dark background before printing.
The pdf is first converted to a bitmap, so change "-density" to match your printer resolution. Also be careful about the RAM required. In this example rgb(0,0,0) is replaced by rgb(255,255,255), change to suit your needs.

print all except first collumn

Find inside files two different patterns in the same line and for matched files show number of matched lines
The option -print0 for find and -0 for grep help prevent issue with weird characters or spaces in filenames. Furthermore with xargs there is no limited number of arguments that find can throw.

put all lines in comment where de word DEBUG is found

Recursively grep for string and format output for vi(m)
This is a big time saver for me. I often grep source code and need to edit the findings. A single highlight of the mouse and middle mouse click (in gnome terminal) and I'm editing the exact line I just found. The color highlighting helps interpret the data.

use the previous commands params in the current command
Here the !!:1 will take the first parameter from the previous command. This can be used in conjunction with other history commands like ! and so on.

Force unmount occupied partition
Alternative if "Lazy unmount" (umount -l) doesn't obey. Alternative for NFS: $ umount -f /media/sdb1 Use with caution: forcing to unmount a busy partition can cause data loss!

rename a file to its md5sum

Text graphing ping output filter
Nasty perl one-liner that provides a sparkline of ping times. If you want a different history than the last 30, just put that value in. It (ab)uses unicode to draw the bars, inspired by https://github.com/joemiller/spark-ping . It's not the most bug-free piece of code, but what it lacks in robustness it makes up for in capability. :) If anyone has any ideas on how to make it more compact or better, I'd love to hear them. I included a ping to google in the command just as an example (and burned up 10 chars doing it!). You should use it with: $ ping example.com | $SPARKLINE_PING_COMMAND

ping a host until it responds, then play a sound, then exit
This allows for sleeping in between pings. Also, espeak needs to be installed.


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