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network usage per process
Nethogs groups bandwidth by process.

Convert CSV to JSON
Replace 'csv_file.csv' with your filename.

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Buffer in order to avoir mistakes with redirections that empty your files
A common mistake in Bash is to write command-line where there's command a reading a file and whose result is redirected to that file. It can be easily avoided because of : 1) warnings "-bash: file.txt: cannot overwrite existing file" 2) options (often "-i") that let the command directly modify the file but I like to have that small function that does the trick by waiting for the first command to end before trying to write into the file. Lots of things could probably done in a better way, if you know one...

recursive search and replace old with new string, inside files
If you can install rpl it's simpler to use and faster than combinations of find, grep and sed. See man rpl for various options. time on above operation: real 0m0.862s, user 0m0.548s, sys 0m0.180s using find + sed: real 0m3.546s, user 0m1.752s, sys 0m1.580s

Change proccess affinity.
Set the affinity of a process to a particular core(s). Arguments for processor include a comma separated list, or a range. (example: 1,2 or 0-3) You can use top in smp mode (Press 1) to see the changes to the affinity.

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Audible warning when a downloading is finished
This command can be set as an alias in ~/.bashrc For example (in my case) I have : alias watchDl='while [ "$(ls $filePart)" != "" ]; do sleep 5; done; mpg123 /home/.../warning.mp3" ' Then I just need to - initialize filePart (e.g. filePart="*bigFile*rar.part") - launch watchDl

Swap a file or dir with quick resotre
This lets you replace a file or directory and quickly revert if something goes wrong. For example, the current version of a website's files are in public_html. Put a new version of the site in public_html~ and execute the command. The names are swapped. If anything goes wrong, execute it again (up arrow or !!).

Backup with versioning
Apart from an exact copy of your recent contents, also keep all earlier versions of files and folders that were modified or deleted. Inspired by EVACopy http://evacopy.sourceforge.net


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