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>

5 files changed, 9 insertions, 9 deletions

diff --git a/solenv/doc/gbuild/doxygen.cfg b/solenv/doc/gbuild/doxygen.cfg
index d66fe0cd1670..605432ab1167 100644
--- a/solenv/doc/gbuild/doxygen.cfg
+++ b/solenv/doc/gbuild/doxygen.cfg
@@ -1661,7 +1661,7 @@ EXTERNAL_GROUPS        = YES
 EXTERNAL_PAGES         = 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
 
diff --git a/solenv/inc/doxygen.cfg b/solenv/inc/doxygen.cfg
index ed50d426549e..ea6ec026d1d5 100644
--- a/solenv/inc/doxygen.cfg
+++ b/solenv/inc/doxygen.cfg
@@ -2085,7 +2085,7 @@ EXTERNAL_GROUPS        = YES
 EXTERNAL_PAGES         = 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').
 # The default file (with absolute path) is: /usr/bin/perl.
 
 PERL_PATH              =
@@ -2300,7 +2300,7 @@ DOT_IMAGE_FORMAT       = svg
 # The default value is: NO.
 # This tag requires that the tag HAVE_DOT is set to YES.
 
-INTERACTIVE_SVG        = YES 
+INTERACTIVE_SVG        = YES
 
 # The DOT_PATH tag can be used to specify the path where the dot tool can be
 # found. If left blank, it is assumed the dot tool can be found in the path.
diff --git a/solenv/inc/doxygen_doc.cfg b/solenv/inc/doxygen_doc.cfg
index 78d2778f7a4b..a53a3791c989 100644
--- a/solenv/inc/doxygen_doc.cfg
+++ b/solenv/inc/doxygen_doc.cfg
@@ -2085,7 +2085,7 @@ EXTERNAL_GROUPS        = YES
 EXTERNAL_PAGES         = 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').
 # The default file (with absolute path) is: /usr/bin/perl.
 
 PERL_PATH              =
@@ -2300,7 +2300,7 @@ DOT_IMAGE_FORMAT       = svg
 # The default value is: NO.
 # This tag requires that the tag HAVE_DOT is set to YES.
 
-INTERACTIVE_SVG        = YES 
+INTERACTIVE_SVG        = YES
 
 # The DOT_PATH tag can be used to specify the path where the dot tool can be
 # found. If left blank, it is assumed the dot tool can be found in the path.
@@ -2398,4 +2398,4 @@ GENERATE_LEGEND        = YES
 # The default value is: YES.
 # This tag requires that the tag HAVE_DOT is set to YES.
 
-DOT_CLEANUP            = YES
\ No newline at end of file
+DOT_CLEANUP            = YES
diff --git a/solenv/inc/doxygen_tag.cfg b/solenv/inc/doxygen_tag.cfg
index 1ba9c17cdbfc..803ec974982d 100644
--- a/solenv/inc/doxygen_tag.cfg
+++ b/solenv/inc/doxygen_tag.cfg
@@ -2085,7 +2085,7 @@ EXTERNAL_GROUPS        = YES
 EXTERNAL_PAGES         = 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').
 # The default file (with absolute path) is: /usr/bin/perl.
 
 PERL_PATH              =
@@ -2300,7 +2300,7 @@ DOT_IMAGE_FORMAT       = svg
 # The default value is: NO.
 # This tag requires that the tag HAVE_DOT is set to YES.
 
-INTERACTIVE_SVG        = YES 
+INTERACTIVE_SVG        = YES
 
 # The DOT_PATH tag can be used to specify the path where the dot tool can be
 # found. If left blank, it is assumed the dot tool can be found in the path.
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