cat -n -s
    cat -s file.txt  | tr -s ' '  | tr -s '\n' | tr 'a' 'Z'
tac / rev

split
    split -b 1G file.tar.xz "file.tar.xz.part."
    cat file.tar.xz.* | tar xJf -
    
chmod 644 755 +x -x
chown -R / chgrp -R

md5sum
  md5sum test.txt
  cat test.txt | md5sum
  echo "testing" | md5sum
  echo -n "testing" | md5sum
  
cp -rv / mv / rm -rf
sync
rsync -av --progress --dry-run -e 'ssh -p22022' --delete

find / updatedb / locate
grep / egrep / fgrep / rgrep
tar / gzip / gunzip / zcat / zless / zgrep / bzip2 ...
head -n / tail -f
hexdump -C / string / strace / ldd
dos2unix
ln -sfn
ls -ctrlh
touch
mkdir -p / cd / rmdir / tree
rm -rf
sort / uniq -c / wc -l
diff -ruN

cd /usr/src
wget "http://www.squid-cache.org/Versions/v6/squid-6.3.tar.gz"
tar xf squid-6.3.tar.gz
cd squid-6.3
./configure --help | less
./configure
make
make install

# Compile & Install
# Config: /usr/local/squid/etc/squid.conf
# Permission
# Start & Check : /usr/local/squid/sbin/squid --help
# Automatic start
# Log rotation

/usr/local/squid/sbin/squid -N
chown -R nobody:nogroup /usr/local/squid/var/logs/

#!/bin/bash
#
# /etc/rc.d/rc.squid
#
PIDFILE="/usr/local/squid/var/run/squid.pid"
TIMEOUT=60

start()
{
  echo -n 'Starting TPROXY Squid . . . '

  PROCESS=$(ps -A | egrep ' squid$')
  if [ "$PROCESS" == "" ]; then
    if [ -f ${PIDFILE} ] ; then
      rm ${PIDFILE}
    fi
  fi
  ulimit -HSn 16384
  ulimit -HSd unlimited
  /usr/local/squid/sbin/squid

  echo "Ok"
}

stop()
{
  echo 'Stoping TPROXY Squid'

  /usr/local/squid/sbin/squid -k shutdown
  TIME=0
  while [ "$TIME" != "$TIMEOUT" ] ; do
    TIME=$(( $TIME + 1 ))
    echo -n $TIME
    if [ "$(pgrep '^squid$')" == "" ]; then
      if [ -f ${PIDFILE} ] ; then
        rm ${PIDFILE}
      fi
      break
    else
      echo -n "."
    fi
    sleep 1
  done
  killall squid &> /dev/null
  killall squid &> /dev/null
  killall squid &> /dev/null
  echo ".Ok"
}

case "$1" in
  'start')
    start
    ;;

  'stop')
    stop
    ;;

  'restart')
    stop
    start
    ;;

  'rotate')
    echo -n 'Rotating TPROXY Squid log files . . . '
    /usr/local/squid/sbin/squid -k rotate
    echo "Ok"
    ;;

  *)
    echo "usage $0 start|stop|restart|rotate"
    ;;

esac

# /etc/logrotate.d/squid
/usr/local/squid/var/logs/access.log {
  daily
  rotate 186
  start 1
  copytruncate
  compress
  compresscmd /usr/bin/bzip2
  compressext .bz2
  compressoptions -sq9
  dateext
  notifempty
  missingok
}

/usr/local/squid/var/logs/cache.log /usr/local/squid/var/logs/store.log {
  daily
  rotate 31
  start 1
  copytruncate
  compress
  compresscmd /usr/bin/bzip2
  compressext .bz2
  compressoptions -sq9
  dateext
  notifempty
  missingok
  sharedscripts
  postrotate
    /usr/local/squid/sbin/squid -k rotate
  endscript
}