8 favorite Unix admin tricks and time-savers

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Killing all processes associated with a particular user (e.g., pkill -u badguy) is a real winner.

The fuser command also ranks high in the list of most useful commands as it provides an easy way to figure out who or what process is using a particular file or directory.

# fuser .
.:                    3326c
# ps -ef | grep 3326
root      3326  3319  0 21:04 pts/0    00:00:00 bash

The "c" following the process ID tells us that the current directory is, well, the current directory for process 3326. The type of access could also have been:

e      executable being run.
f      open file. f is omitted in default display mode.
F      open file for writing. F is omitted in default display mode.
r      root directory.
m      mmap'ed file or shared library.

Being a long-time Unix sysadmin, I'm entitled to my moments in extreme laziness and creating an alias for the clear command allows me to clear my screen with two strokes.

alias c=clear

I also sometimes use aliases to insert that pesky "sudo" into commands that I know I'm going to run or to forgive me if I get the commands wrong (hmm, is it useradd or adduser?).

if [ $UID -ne 0 ]; then
    alias reboot='sudo reboot'
    alias update='sudo apt-get upgrade'
    alias useradd='sudo /usr/sbin/useradd'
    alias adduser='sudo /usr/sbin/useradd'
    alias userdel='sudo /usr/sbin/userdel -f'
    alias deluser='sudo /usr/sbin/userdel -f'
fi

I sure can't end this post without showing appreciation for the unalias command. This is especially useful when I'm working on systems that I don't manage. The rm command is so often aliased to "rm -i" and for good reason. Still, if I'm being my careful best, I may not want to be prompted 87 times to assure the system that, yes, I really mean to delete the files I am asking it to delete. The easy turning off of even a well-meant alias keeps me calm.

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