From 8e78376cd4b725a029dbc98e1ed6eb100cedf14a Mon Sep 17 00:00:00 2001 From: Eli Schwartz Date: Wed, 12 Mar 2025 09:30:38 -0400 Subject: [PATCH] build: fix building manpages on systems where asciidoc is already installed It doesn't really make sense to run one command that isn't installed, to see if another command is installed. Even though I have a2x installed, the build fails with: ``` make: Entering directory '/var/tmp/portage/dev-vcs/git-absorb-0.7.0/work/git-absorb-0.7.0/Documentation' make: which: No such file or directory Makefile:4: *** "No a2x in PATH; install asciidoc.". Stop. ``` 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. Several Linux distros which *do* currently ship a (decent quality) `which` utility in their default install are looking to get rid of it: - Gentoo: https://bugs.gentoo.org/646588 - Debian: https://lwn.net/Articles/874049/ --- Documentation/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Documentation/Makefile b/Documentation/Makefile index 3056326..b642af1 100644 --- a/Documentation/Makefile +++ b/Documentation/Makefile @@ -1,7 +1,7 @@ build-manpage: git-absorb.1 git-absorb.1: git-absorb.adoc - $(if $(shell which a2x),,$(error "No a2x in PATH; install asciidoc.")) + $(if $(shell command -v a2x),,$(error "No a2x in PATH; install asciidoc.")) $(info Building manpage. This may take a few moments...) a2x -L -d manpage -f manpage git-absorb.adoc --attribute man-version=${GA_VERSION}