Commands by rsimpson (3)

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Write comments to your history.
A null operation with the name 'comment', allowing comments to be written to HISTFILE. Prepending '#' to a command will *not* write the command to the history file, although it will be available for the current session, thus '#' is not useful for keeping track of comments past the current session.

Show LAN IP with ip(8)
$ ip address show | grep eth0 | sed '1d' | awk '{print $2}' does the same, but shows network-prefix.

Find and remove core files

Easily decode unix-time (funtion)
More recent versions of the date command finally have the ability to decode the unix epoch time into a human readable date. This function makes it simple to utilize this feature quickly.

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"

Reconstruct standard permissions for directories and files in current directory

Find Duplicate Files (based on size first, then MD5 hash)
Finds duplicates based on MD5 sum. Compares only files with the same size. Performance improvements on: $find -not -empty -type f -printf "%s\n" | sort -rn | uniq -d | xargs -I{} -n1 find -type f -size {}c -print0 | xargs -0 md5sum | sort | uniq -w32 --all-repeated=separate The new version takes around 3 seconds where the old version took around 17 minutes. The bottle neck in the old command was the second find. It searches for the files with the specified file size. The new version keeps the file path and size from the beginning.

convert single digit to double digits
each number in a file name gets expanded to the number of digets provided as arg_1 of the arguments in rjust_file_nums. Put the funciton in the .bashrc file. Be sure to $ source ~/.bashrc so that the function will be accessible from bash.

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"

move a lot of files over ssh
Useful to move many files (thousands or millions files) over ssh. Faster than scp because this way you save a lot of tcp connection establishments (syn/ack packets). If using a fast lan (I have just tested gigabyte ethernet) it is faster to not compress the data so the command would be: tar -cf - /home/user/test | ssh user@sshServer 'cd /tmp; tar xf -'


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