program demo_regexec ! read regular expression from command line and look for it in lines read from stdin. use M_regex, only: regex_type, regcomp, regexec, regfree implicit none integer :: command_argument_length character(len=:),allocatable :: command_argument character(len=1024) :: input_line type(regex_type) :: regex logical :: match integer :: ios call get_command_argument(number=1,length=command_argument_length) allocate(character(len=command_argument_length) :: command_argument) call get_command_argument(1, command_argument) call regcomp(regex,command_argument,'xn') ! compile up regular expression INFINITE: do read(*,'(a)',iostat=ios)input_line if(ios.ne.0)exit INFINITE match=regexec(regex,input_line) ! look for a match in (remaining) string if(.not.match)cycle INFINITE ! if no match found go for next line write(*,'(a)') trim(input_line) ! show line with match enddo INFINITE call regfree(regex) ! free memory used for compiled regular expression end program demo_regexec