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Perl oneliner to print access rights in octal format
This prints file access rights in octal - useful when "stat" is unavailable.

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"

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"

Find Duplicate Files (based on size first, then MD5 hash)
This dup finder saves time by comparing size first, then md5sum, it doesn't delete anything, just lists them.

Harder, Faster, Stronger SSH clients
We force IPv4, compress the stream, specify the cypher stream to be Blowfish. I suppose you could use aes256-ctr as well for cypher spec. I'm of course leaving out things like master control sessions and such as that may not be available on your shell although that would speed things up as well.

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)

run command on a group of nodes in parallel redirecting outputs
Do the same as pssh, just in shell syntax. Put your hosts in hostlist, one per line. Command outputs are gathered in output and error directories.

Shows space used by each directory of the root filesystem excluding mountpoints/external filesystems (and sort the output)
Useful to see at glance which directory under the root file is using most space

Find the package that installed a command

Check a server is up. If it isn't mail me.
This version uses netcat to check a particular service.


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