====== Admin - Fu ======

===== PROCESSES =====

Kill all processes belonging to a user

<code bash>
ps wwwwuax|awk '/command/ { printf("kill -9 %s\n",$2) }'|/bin/sh

</code>

Remove all at jobs

<code bash>
atq | sed 's_\([0-9]\{1,8\}\).*_\1_g' | xargs atrm

</code>

Display the top ten running processes - sorted by memory usage

    ps aux | sort -nk +4 | tail

Slow down IO heavy process

    slow () { 
        [ -n $1 ] && \
        while ps -p $1 >/dev/null ; do 
            kill -STOP  $1
            sleep 1
            kill -CONT $1
            sleep 1
        done &
    }

===== PACKAGES =====

Extract list of packages installed on one server and generate ‘apt’
command to install them on a new server

    dpkg --list | rgrep ii | cut -d" " -f3 | sed ':a;N;$!ba;s/\n/ /g' | \
        sed 's/^\(.\)/apt-get install \1/'

Display a list of RPMs installed on a particular date

<code sh>
rpm -qa --queryformat '%{installtime}  \"%{vendor}\" \
    %{name}-%{version}-%{release}  %{installtime:date}\n' | grep "Thu 05 Mar"

</code>

Display installed RPMs in size order, largest first

<code sh>
rpm -qa --queryformat '%{size} %{name}-%{version}-%{release}\n' | \
    sort -k 1,1 -rn | nl 

</code>

===== SWAP =====

Create an emergency swapfile when the existing swap space is getting
tight

<code sh>
sudo dd if=/dev/zero of=/swapfile bs=1024 count=1024000
sudo mkswap /swapfile
sudo swapon /swapfile
</code>