process_open_write(3fm) - [M_process] open a process for writing using a POSIX interface (LICENSE:PD)
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subroutine process_open_write(cmd,fp,ierr)
character(len=*) :: cmd type(streampointer) :: fp integer :: ierr
The M_process Fortran procedures use the ISO_C_BINDING interface to define Fortran-callable versions of the C procedures popen(3c)/pclose(3c) and fgets(3c)/fputs(3c). A set of record-oriented wrapper routines are then used to create a simple Fortran-callable interface.A POSIX C interface is generally available but may require using a Linux subwindow or an application such as CygWin on MSWindows platforms.
See "M_process" for an extended description.
maximum character value length is currently 4096
cmd command passed to system to start process fp C file pointer returned by process_open_*() ierr error flag returned.
o process_writeline(3f) : negative indicates an error o process_readline(3f) : Non-zero indicates an error
This example shows a routine to write lines to the stdin of a system process
program demo_process_open_write use, intrinsic :: iso_fortran_env, only : & & stdin=>input_unit, & & stdout=>output_unit, & & stderr=>error_unit use M_process,only: process_open_write, process_writeline use M_process,only: streampointer, process_close implicit none type(streampointer) :: fp ! line of data to write character(len=4096) :: line integer :: ierr integer :: i ! open process to write to call process_open_write(cat -n,fp,ierr) write(stdout,*)OPENWTEST: process is opened with status ,ierr ! remember C and Fortran I/O are often independent of each other flush(stdout) ierr=0 line=xxxxxxxxxxxxxxxxxxxxxxxxxxx do i=1,10 ! write a line to the process call process_writeline(trim(line),fp,ierr) if(ierr.lt.0)then write(stdout,*)OPENWTEST: ierr is ,ierr exit endif enddo call process_close(fp,ierr) write(stdout,*)OPENWTEST: process closed with status ,ierr end program demo_process_open_writeSample output:
>OPENWTEST: process is opened with status 0 > 1 xxxxxxxxxxxxxxxxxxxxxxxxxxx > 2 xxxxxxxxxxxxxxxxxxxxxxxxxxx > 3 xxxxxxxxxxxxxxxxxxxxxxxxxxx > 4 xxxxxxxxxxxxxxxxxxxxxxxxxxx > 5 xxxxxxxxxxxxxxxxxxxxxxxxxxx > 6 xxxxxxxxxxxxxxxxxxxxxxxxxxx > 7 xxxxxxxxxxxxxxxxxxxxxxxxxxx > 8 xxxxxxxxxxxxxxxxxxxxxxxxxxx > 9 xxxxxxxxxxxxxxxxxxxxxxxxxxx > 10 xxxxxxxxxxxxxxxxxxxxxxxxxxx >OPENWTEST: process closed with status 0
o PIPES: pipe(3c), popen(3c), pclose(3c), fflush(3c) o NAMED PIPES: mkfifo(3c), mknod(3c) o SUBPROCESSES: fork(3c) o OTHER: fflush(3c)
John S. Urban
Public Domain
Nemo Release 3.1 | process_open_write (3) | February 23, 2025 |