tcpdump -i eth0 udp

man snmpd.conf | less +/'Process Monitoring'

socat tcp-listen:110,fork,reuseaddr tcp:some-host:143

        <Directory /var/www/your-directory>
                Options -Indexes
        </Directory>

#! /bin/sh -
user=$1; shift
for server do
  ssh "$user@$server" < Sourcefile '
     cat > directory/TargetFile && /etc/init.d/daemon restart'
done

telnet your-server the-port
EHLO localhost
mail from: your-address
rcpt to: foo.bar@gmail.com

strace -vfTtto strace.log cmd args

LogLevel debug

$ grep /dev/full Documentation/devices.txt
                  7 = /dev/full         Returns ENOSPC on write

echo kernel.sysrq=511 > /etc/sysctl.d/sysrq.conf

find . -type f -exec grep -lZ RTG78 {} + | xargs -r0 sed -i 's/RTG78/something/g'

find . -type f -exec grep -alZ RTG78 {} + | xargs -r0 perl -pi -e 's/RTG78/something/g'

rsync -e 'ssh -c blowfish -o BatchMode=yes -o StrictHostKeyChecking=yes -o 

ServerAliveInterval=10 -p 2222 -ax' 
  --archive --xattrs --hard-links --numeric-ids --sparse --acls  --compress-level=3

echo test > /dev/kmsg

strace -fe network your program and its arguments here

find . -printf '%s\t%p\n' | sort -rn | head -30

ls -ldU -- **/*(DOL[1,30])

sed 's/[[:space:]]//'

perl -MSocket -e 'exit 1 unless Socket::inet_pton(AF_INET, $ARGV[0])' address-to-check

perl -MSocket -e 'exit 1 unless Socket::inet_pton(AF_INET6, $ARGV[0])' address-to-check

        <Directory /var/www/your-directory>
                Options -Indexes
        </Directory>

#! /bin/sh -
user=$1; shift
for server do
  ssh "$user@$server" < Sourcefile '
     cat > directory/TargetFile && /etc/init.d/daemon restart'
done

echo kernel.sysrq=511 > /etc/sysctl.d/sysrq.conf

find . -printf '%s\t%p\n' | sort -rn | head -30

ls -ldU -- **/*(DOL[1,30])