#!/bin/bash

# countprocs.sh - counts each users' processes matching a given regex
# Licensed under the terms of the GNU GPLv3 or later
# Proprietary Software Must Perish!

# AUTHOR: Johannes Truschnigg ( johannes.truschnigg@gmx.at || http://johannes.truschnigg.info )

# some sanity checks; some implementations of `ps` still might fail at a later point
(which pgrep && which ps && which printf || echo 1>&2 "please install these missing programs.") >/dev/null || exit 1;
[ "${BASH_VERSINFO[0]:-0}" -lt 3 ] && echo 1>&2 "you need bash version 3 or later to run this script." && exit 1;

declare -a pid_array;
declare -i pid_owner pid_key;

# process substitution used to avoid messing with a pipe
while read pid_owner;
do
pid_array[pid_owner]=$((${pid_array[pid_owner]} + 1));
done < <(for i in $(pgrep "${1:-.}");
do ps --no-headers -p "$i" -o "uid";
done)

# ${!array[*]} returns keys of an array as of bash 3.x and above
for pid_key in ${!pid_array[*]};
do printf "UID %8d: %8d procs\n" "$pid_key" "${pid_array[pid_key]}";
done