Dtyjlui

I have a simple script as below which checks if fail2ban service is running or not on Ubuntu 18.04:

#!/bin/bash



# Script to check if fail2ban service is running



if pgrep -x "fail2ban" > /dev/null

then

   echo "Fail2ban is running"

else

   echo "Fail2ban is not running"

fi

I have installed fail2ban in a test VM and is running on the VM. Here is a screenshot of systemctl status command.

But, when the run the above script, I get the result that "Fail2ban is not running". I am not sure if is with the script. I tried ps aux command too instead of pgrep. But, I still get the same result.

You asked pgrep to exactly (-x) search for a process called fail2ban
but the output of systemctl status shows it is called
/usr/bin/python3 instead.

To check whether a systemd unit is running use

systemctl is-active --quiet fail2ban

That is:

if systemctl is-active --quiet fail2ban; then

    echo "running"

else

    echo "not running"

fi

The following shellscript running combines the result of

• 
  systemctl is-active and


• ps -ef | ... | grep

in order to detect if a certain program (or a program name containing the search string) is running or not.

#!/bin/bash



if [ $# -ne 1 ]

then

 echo "Usage:    $0 <program-name>

          $0 <part of program name>

Examples: $0 firefox

          $0 term

          $0 dbus

          $0 'dbus-daemon --session'"

 exit

fi



inversvid="033[7m"

resetvid="033[0m"

redback="033[1;37;41m"

greenback="033[1;37;42m"

blueback="033[1;37;44m"



runn=false

tmpfil=$(mktemp)



# check by systemctl



systemctl is-active --quiet "$1"

if [ $? -eq 0 ]

then

 echo "systemctl is-active:"

 runn=true

fi



# check by ps



ps -ef | tr -s ' ' ' ' | cut -d ' ' -f 8-9 | grep "$1" | grep -vE -e "$0 $1" -e "grep $1" | sort -u > "$tmpfil"



tmpstr=$(head -n1 $tmpfil)

#echo "$tmpstr"

if [ "$tmpstr" == "$1" ] || [ "${tmpstr##*/}" == "$1" ] || [ "${1##*/}" == "${0##*/}" ]

then

 echo "ps -ef: active:"

 runn=true

elif test -s "$tmpfil"

then

 if $runn

 then

  echo "----- consider also ---------------------------------------------"

  cat "$tmpfil"

  echo "-----------------------------------------------------------------"

 else

  echo "----- try with: -------------------------------------------------"

  cat "$tmpfil"

  echo "-----------------------------------------------------------------"

 fi

fi



if $runn

then

 echo -e "$greenback $1 is running $resetvid"

else

 inpath=$(which "$1")

 if [ "$inpath" == "" ]

 then

  echo -e "$redback no path found to $1 $resetvid"

 else

  echo -e "$blueback $1 is not running $resetvid"

 fi

fi

Make it executable and put it in a directory in PATH, if you wish. I put it into my bin directory and can used it without any path.

Usage:

$ running 

Usage:    /home/sudodus/bin/running <program-name>

          /home/sudodus/bin/running <part of program name>

Examples: /home/sudodus/bin/running firefox

          /home/sudodus/bin/running term

          /home/sudodus/bin/running dbus

          /home/sudodus/bin/running 'dbus-daemon --session'

Examples:

$ running firefox

ps -ef: active:

 firefox is running   # green background - running



$ running term

----- try with: -------------------------------------------------

/usr/lib/gnome-terminal/gnome-terminal-server

xterm

x-terminal-emulator

-----------------------------------------------------------------

 no path found to term   # red background - path not found



$ running dbus

systemctl is-active:

----- consider also ---------------------------------------------

/usr/bin/dbus-daemon --session

/usr/bin/dbus-daemon --syslog

/usr/bin/dbus-daemon --system

/usr/bin/fcitx-dbus-watcher unix:abstract=/tmp/dbus-Nm2MSvuTZF,guid=25bad8d51276d088045625055c425080

-----------------------------------------------------------------

 dbus is running   # green background



$ running 'dbus-daemon --session'

ps -ef: active:

 dbus-daemon --session is running   # green background



$ running libreoffice

 libreoffice is not running    # blue background - not running