Commands by oldo (8)

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renames multiple files that match the pattern
Useful when you want to quickly rename a bunch of files.

Copy ssh keys to user@host to enable password-less ssh logins.
To generate the keys use the command ssh-keygen

Get a list of IP Addresses that have failed to login via SSH
This command shows a sorted list of the IP addresses from which there have been authentication errors via SSH (possible script kiddies trying to gain access to your server), it eliminates duplicates so it's easier to read, but you can remove the "uniq" command at the end, or even do a "uniq -c" to have a count of how many times each IP address shows in the log (the path to the log may vary from system to system)

Recursively scan directories for mp3s and pass them to mplayer
The command first deletes any old playlist calles playlist.tmp under /tmp. After that it recursively searches all direcotries under ~/mp3 and stores the result in /tmp/playlist.tmp. After havin created the playlist, the command will execute mplayer which will shuffle through the playlist. This command is aliased to m is aliased to `rm -rf /tmp/playlist.tmp && find ~/mp3 -name *.mp3 > /tmp/playlist.tmp && mplayer -playlist /tmp/playlist.tmp -shuffle -loop 0 | grep Playing' in my ~/.bashrc.

write text or append to a file
If you just want to write or append some text to a file without having to run a text editor, run this command. After running the command, start typing away. To exit, type . on a line by itself. Replacing the >> with a single > will let you overwrite your file.

AWK Calculator

Find the package a command belongs to on debian-based distros

Count number of files in a directory

Compare copies of a file with md5

bulk rename files with sed, one-liner
Far from my favorite, but works in sh and with an old sed that doesn't support '-E'

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