If you need script to see if specified process is running, its easy to grep it from ps aux.
Problem here is that you can see your grep process which has your process as parameter. Script that relays on exit code ends up always being successful since grep process is on the list. You can easily fix this problem by adding additional pipe trough grep with -v grep parameter.
-v option is also --invert-match
Its a lot easier to do this by using pgrep.
pgrep scans running processes and returns process pid into your stdout.
m@box:~$ ps aux | grep mysqld
mysql 1090 0.0 3.1 322660 48892 ? Ssl 19:53 0:00 /usr/sbin/mysqld
m 1903 0.0 0.0 4384 808 pts/0 S+ 20:29 0:00 grep --color=auto mysqld
Problem here is that you can see your grep process which has your process as parameter. Script that relays on exit code ends up always being successful since grep process is on the list. You can easily fix this problem by adding additional pipe trough grep with -v grep parameter.
-v option is also --invert-match
ps aux | grep mysqld | grep -v grep 1>/dev/null&& echo Process is runing || echo Process is not running
Its a lot easier to do this by using pgrep.
pgrep scans running processes and returns process pid into your stdout.
m@box:~$ pgrep mysqld 1>/dev/null&& echo Process is runing || echo Process is not running
Process is runing 