Bash script to check multiple running processes - linux

Question

I'm made the following code to determine if a process is running:
#!/bin/bash
ps cax | grep 'Nginx' > /dev/null
if [ $? -eq 0 ]; then
echo "Process is running."
else
echo "Process is not running."
fi
I would like to use my code to check multiple processes and use a list as input (see below), but getting stuck in the foreach loop.
CHECK_PROCESS=nginx, mysql, etc
What is the correct way to use a foreach loop to check multiple processes?

Answer 1

If your system has pgrep installed, you'd better use it instead of the greping of the output of ps.
Regarding you're question, how to loop through a list of processes, you'd better use an array. A working example might be something along these lines:
(Remark: avoid capitalized variables, this is an awfully bad bash practice):
#!/bin/bash
# Define an array of processes to be checked.
# If properly quoted, these may contain spaces
check_process=( "nginx" "mysql" "etc" )
for p in "${check_process[#]}"; do
if pgrep "$p" > /dev/null; then
echo "Process \`$p' is running"
else
echo "Process \`$p' is not running"
fi
done
Cheers!

Answer 2

Use a separated list of of processes:
#!/bin/bash
PROC="nginx mysql ..."
for p in $PROC
do
ps cax | grep $p > /dev/null
if [ $? -eq 0 ]; then
echo "Process $p is running."
else
echo "Process $p is not running."
fi
done
If you simply want to see if either one of them is running, then you don't need loo. Just give the list to grep:
ps cax | grep -E "Nginx|mysql|etc" > /dev/null

Answer 3

Create file chkproc.sh
#!/bin/bash
for name in $#; do
echo -n "$name: "
pgrep $name > /dev/null && echo "running" || echo "not running"
done
And then run:
$ ./chkproc.sh nginx mysql etc
nginx: not running
mysql: running
etc: not running
Unless you have some old or "weird" system you should have pgrep available.