Terminating Processes
- Generally, all process terminates on their own. In this example, find command will terminate when it completed its task:
find /home -name "*.c" 2>error.log 1>filelists &
- You can terminate foreground process by pressing CTRL+C. It will send a TERM signal to the process. In this example, ls -R is running on screen:
ls -R /
- To terminate simply press CTRL+C (hold down CTRL key and press C) to send an in interrupt signal to the ls command.
- To terminate unwanted background process use kill command with -9 signal as described in sending signal to processes section:
kill -TERM pid
kill -KILL pid
- To stop (suspend) a foreground process hit CTRL+Z (hold down CTRL key and press z). To resume the foreground process use the fg command, enter:
fg jobid
fg 1
fg %
Example
Create a shell script called phpjail.sh. This script is used to start php service in a jail. This is done to improve Apache or Lighttpd web server security. This script demonstrates the usage of the pgrep command, pkill commands, and other skilled you've learned so far.
#!/bin/sh
# A shell script to start / stop php-cgi process.
# Author: Vivek Gite <vivek@gite.in>
# Last updated on June-23-2007.
# ----------------------------------------------
fFCGI=/usr/bin/spawn-fcgi
fIP=127.0.0.1
fPORT=9000
fUSER=phpjail
fGROUP=phpjail
fCHILD=10
fJAILDIR=/phpjail
fPID=/var/run/fcgi.php.pid
fPHPCGI=/usr/bin/php-cgi
# path to binary files.
PKILL=/usr/bin/pkill
RM=/bin/rm
PGREP=/usr/bin/pgrep
GREP=/bin/grep
ID=/usr/bin/id
# Must be run as root else die
[ $(${ID} -u) -eq 0 ] || { echo "$0: Only root may run this script."; exit 1; }
# Jail user must exits else die
${GREP} -q $fUSER /etc/passwd || { echo "$0: User $fUSER not found in /etc/passwd."; exit 2; }
# Jail group must exits else die
${GREP} -q $fGROUP /etc/passwd || { echo "$0: Group $fGROUP not found in /etc/group."; exit 3; }
# Jail directory must exits else die
[ ! -d ${fJAILDIR} ] && { echo "$0: php-cgi jail directory \"${fJAILDIR}\" not found."; exit 4; }
# Use case to make decision
case "$1" in
start)
# start php-cgi in jail at given IP and server port
$fFCGI -a $fIP -p $fPORT -u $fUSER -g $fGROUP -C $fCHILD -c $fJAILDIR -P $fPID -- $fPHPCGI
[ $? -eq 0 ] && echo "Starting php-cgi .. [ OK ]" || echo "Starting php-cgi .. [ FAILED ]"
;;
stop)
# make sure php-cgi is running
read line < "$fPID"
if [ -d /proc/$line ]
then
# kill php-cgi owned by user
${PKILL} -KILL -u $fUSER php-cgi
[ $? -eq 0 ] && echo "Stopping php-cgi .. [ OK ]" \
|| echo "Stopping php-cgi .. [ FAILED ]"
${RM} -f $fPID
else
echo "$0: php-cgi is not running."
fi
;;
status)
# find out if php-cgi is running or not
${PGREP} -u ${fUSER} php-cgi >/dev/null 2>&1
[ $? -eq 0 ] && echo "$0: php-cgi is running at $fIP:$fPORT" \
|| echo "$0: php-cgi is not running at $fIP:$fPORT"
;;
*)
# display usage
echo "Usage: $0 {start|stop|status}"
esac
I highly recommend the following two articles which deals with php and web server security:
