C Library Functions - system_readline (3)
NAME
system_readline(3f) - [M_readline] Call readline(3c) from Fortran (LICENSE:PD)
CONTENTS
Synopsis
Description
Examples
Author
License
SYNOPSIS
character(kind=c_char,len=*),intent(in) :: prompt character(kind=c_char,len=*),intent(out) :: line
DESCRIPTION
The system_readline(3f) uses the ISO_C_BINDING module to create a binding to the GNU readline(3c) procedure from Fortran programs.
EXAMPLES
The test program is basically just a read loop that prompts for lines of input read with readline(3c). You can edit the line being read with readline(3c) per its documentation. At a minimum, you can probably move around the line with the left and right arrow keys, and insert characters by typing them wherever you moved the cursor to, and use the DEL/ RUBOUT key to delete characters and such. If you use a GNU/Linux shell with command line editing, you are probably familiar with readline(3c)’s function.
It quits if you enter ’q’ on an input line, and it dumps the history if you enter ’h’.
It is presented here as a Bourne shell script that creates the necessary files and does a "compile, load, and go"
the test program
program demo_system_readline
use M_readline, only : system_readline
implicit none
character(len=4096) :: line
integer :: cstat
character(len=256) :: sstat
call intro()
do
call system_readline(line,’readline>’) ! read editable input line
if(line.eq.’q’) then
stop
elseif(line.eq.’?’) then
call intro()
else
call execute_command_line(trim(line),cmdstat=cstat,cmdmsg=sstat)
endif
enddo
contains
subroutine intro()
integer :: i
character(len=*),parameter :: help_text(*)=[character(len=80) :: &
’--------------------------------------------------------------------------------’ ,&
’ Your input lines are now editable using the GNU readline(3c) procedure.’ ,&
’ By default, up-arrow and down-arrow go through the history lines; left and ’ ,&
’ and right arrow keys and the delete key and just typing characters let you do’ ,&
’ simple editing. Far more input control is available. See the mon(1) page for’ ,&
’ readline(3c) for more information.’ ,&
’ --------------------------------------------------------------------------------’,&
’ "q" quits; "h" display history, "?" displays this help text’ ,&
’ Enter commands and then edit them...’ ,&
’ ’ ]
write(*,’(a)’)(trim(help_text(i)),i=1,size(help_text))
end subroutine intro
end program demo_system_readline
AUTHOR
John S. Urban
LICENSE
Public DomainAlthough this interface to readline(3c) is released as Public Domain, note that the Readline library itself is free software, distributed under the terms of the [GNU] General Public License, version 2.
| Nemo Release 3.1 | system_readline (3) | August 28, 2026 |
