Finding process count in Linux via command line

On systems that have pgrep available, the -c option returns a count of the number of processes that match the given name

pgrep -c command_name

Note that this is a grep-style match, not an exact match, so e.g. pgrep sh will also match bash processes. If you want an exact match, also use the -x option.

If pgrep is not available, you can use ps and wc.

ps -C command_name --no-headers | wc -l

The -C option to ps takes command_name as an argument, and the program prints a table of information about processes whose executable name matches the given command name. This is an exact match, not grep-style. The --no-headers option suppresses the headers of the table, which are normally printed as the first line. With --no-headers, you get one line per process matched. Then wc -l counts and prints the number of lines in its input.

result=`ps -Al | grep command-name | wc -l`
echo $result

ps -Al | grep -c bash