``` ghci> import System.Process ghci> let cmd = "pgrep" ghci> let args = ["firefox"] ghci> let input = "" ghci> readProcessWithExitCode cmd args input Loading package array-0.4.0.1 ... linking ... done. Loading package deepseq-1.3.0.1 ... linking ... done. Loading package bytestring-0.10.0.2 ... linking ... done. Loading package old-locale-1.0.0.5 ... linking ... done. Loading package time-1.4.0.1 ... linking ... done. Loading package unix-2.6.0.1 ... linking ... done. Loading package filepath-1.3.0.1 ... linking ... done. Loading package directory-1.2.0.1 ... linking ... done. Loading package process-1.1.0.2 ... linking ... done. (ExitSuccess,"3144\n","") ```