#!/bin/bash
all_process_pid=(`pidof xxxx`)
process_num=${all_process_pid[*]}
if [ ${process_num}  -eq 1 ];then
    echo "normal"
else
    echo "unnormal"
fi
exit

[root@probe: ~]$ pidof  -h
pidof usage: [options] <program-name>

 -c           Return PIDs with the same root directory
 -d <sep>     Use the provided character as output separator
 -h           Display this help text
 -n           Avoid using stat system function on network shares
 -o <pid>     Omit results with a given PID
 -q           Quiet mode. Do not display output
 -s           Only return one PID
 -x           Return PIDs of shells running scripts with a matching name
 -z           List zombie and I/O waiting processes. May cause pidof to hang.

[zy@fedora ~]$ pidof -V
pidof from procps-ng 3.3.17
[zy@fedora ~]$ pidof -h

Usage:
 pidof [options] [program [...]]

Options:
 -s, --single-shot         return one PID only
 -c, --check-root          omit processes with different root
 -q,                       quiet mode, only set the exit code
 -w, --with-workers        show kernel workers too
 -x                        also find shells running the named scripts
 -o, --omit-pid <PID,...>  omit processes with PID
 -S, --separator SEP       use SEP as separator put between PIDs
 -h, --help     display this help and exit
 -V, --version  output version information and exit