use portable "command -v" to detect installed programs, part 5

The "which" utility is not guaranteed to be installed either, and if it
is, its behavior is not portable either. This means that when various
programs are installed, the `which` check will report a fatal error
because the which tool did not exist and the shell returned a nonzero
status when attempting to fork+exec. If it did exist, it might not be an
implementation of `which` that returns nonzero when commands do not
exist.

The general scripting suggestion is to use the "command -v" shell
builtin; this is required to exist in all POSIX 2008 compliant shells,
and is thus guaranteed to work everywhere.

For some in-depth discussions on the topic, see:
- https://mywiki.wooledge.org/BashFAQ/081
- https://unix.stackexchange.com/questions/85249/why-not-use-which-what-to-use-then/85250#85250

Examples of open-source shells likely to be installed as /bin/sh on
Linux, which implement the 15-year-old standard: ash, bash, busybox,
dash, ksh, mksh and zsh.

This commit updates documentation to no longer suggest a bad practice
that will confuse the reader when it doesn't work.

Change-Id: I0ed5ced353124919c7e09912c6d4d5aea146fa33
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/160666
Tested-by: Ilmari Lauhakangas <ilmari.lauhakangas@libreoffice.org>
Reviewed-by: Ilmari Lauhakangas <ilmari.lauhakangas@libreoffice.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/writerfilter/documentation/doxygen/Doxyfile b/writerfilter/documentation/doxygen/Doxyfile
index 15414b8287c6..6ae1ac4c02aa 100644
--- a/writerfilter/documentation/doxygen/Doxyfile
+++ b/writerfilter/documentation/doxygen/Doxyfile
@@ -1078,7 +1078,7 @@ ALLEXTERNALS           = NO
 EXTERNAL_GROUPS        = YES
 
 # The PERL_PATH should be the absolute path and name of the perl script
-# interpreter (i.e. the result of `which perl').
+# interpreter (i.e. the result of `command -v perl').
 
 PERL_PATH              = /usr/bin/perl