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;;; node.scm -- Distributed computing node
;; Copyright (C) 2016 Artyom V. Poptsov <poptsov.artyom@gmail.com>
;;
;; This file is a part of Guile-SSH.
;;
;; Guile-SSH is free software: you can redistribute it and/or
;; modify it under the terms of the GNU General Public License as
;; published by the Free Software Foundation, either version 3 of the
;; License, or (at your option) any later version.
;;
;; Guile-SSH is distributed in the hope that it will be useful, but
;; WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;; General Public License for more details.
;;
;; You should have received a copy of the GNU General Public License
;; along with Guile-SSH. If not, see
;; <http://www.gnu.org/licenses/>.
;;; Commentary:
;; Remote shell.
;;
;; The module provides the following procedures:
;; rexec
;; which
;; pgrep
;; fallback-pgrep
;;
;; See the Info documentation for detailed description of these exceptions and
;; aforementioned procedures.
;;; Code:
(define-module (ssh shell)
#:use-module (ice-9 rdelim)
#:use-module (ice-9 regex)
#:use-module (ssh channel)
#:use-module (ssh popen)
#:export (rexec which pgrep fallback-pgrep command-available?))
;;;
;; TODO: Move to some other file do prevent duplicating of the procedure in
;; (ssh dist node).
(define (eof-or-null? str)
"Return #t if a STR is an EOF object or an empty string, #f otherwise."
(or (eof-object? str) (string-null? str)))
;;;
(define (rexec session cmd)
"Execute a command CMD on the remote side. Return two values: list of
output lines returned by CMD and its exit code."
(let ((channel (open-remote-input-pipe session cmd)))
(values (let loop ((line (read-line channel))
(result '()))
(if (eof-or-null? line)
(reverse result)
(loop (read-line channel)
(cons line result))))
(channel-get-exit-status channel))))
;;;
(define (which session program-name)
"Check if a PROGRAM-NAME is available on a remote side. Return two values:
a check result and a return code."
(rexec session (format #f "which '~a'" program-name)))
(define* (pgrep session pattern #:key (full? #f))
"Check if a process with a PATTERN cmdline is available on a NODE.
Return two values: a check result and a return code."
(rexec session (format #f "pgrep ~a '~a'"
(if full? "--full" "")
pattern)))
(define (fallback-pgrep session pattern)
"Guile-SSH implementation of 'pgrep' that uses pure bash and '/proc'
filesystem. Check if a process with a PATTERN cmdline is available on a NODE.
Return two values: a check result and a return code."
(define (make-command ptrn)
(format #f "\
echo '
for p in $(ls /proc); do
if [[ \"$p\" =~ ^[0-9]+ ]]; then
name=$(cat \"/proc/$p/status\" 2>/dev/null | head -1);
if [[ \"$name\" =~~ Name:.*guile ]]; then
cmdline=$(cat \"/proc/$p/cmdline\");
if [[ \"$cmdline\" =~~ ~a ]]; then
exit 0;
fi;
fi;
fi;
done;
exit 1;
' | bash
" ptrn))
(let ((ptrn (string-append (regexp-substitute/global #f " " pattern
'pre "?" 'post)
".*")))
(rexec session (make-command ptrn))))
(define (command-available? session command)
"check if COMMAND is available on a remote side."
(receive (result rc)
(which session command)
(zero? rc)))
;;; shell.scm ends here.
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