On 10/9/20 10:46 AM, Cristian Morales Vega wrote: > I would like to send some patches making pkg-config files relocatable. > pkg-config offers the "pcfiledir" variable to do this. > The thing is that I need to be able to obtain prefix, libdir, > includedir, etc. relative to the directory where the .pc file gets > installed. I can easily do this with realpath, from coreutils, but > it's not POSIX and I'm not sure people will accept such a dependency. > The use of automake per se has no dependency to coreutils, does it? > > There is any way to obtain the path of one directory relative to > another in automake without adding a new dependency? "realpath" > implemented as a m4 macro, maybe?
https://stackoverflow.com/questions/2564634/convert-absolute-path-into-relative-path-given-a-current-directory-using-bash suggests that it can be scripted in portable shell (although I did not test if it has odd corner cases when one or the other input contains things like foo/../bar or symlinks): #!/bin/sh relpath () { [ $# -ge 1 ] && [ $# -le 2 ] || return 1 current="${2:+"$1"}" target="${2:-"$1"}" [ "$target" != . ] || target=/ target="/${target##/}" [ "$current" != . ] || current=/ current="${current:="/"}" current="/${current##/}" appendix="${target##/}" relative='' while appendix="${target#"$current"/}" [ "$current" != '/' ] && [ "$appendix" = "$target" ]; do if [ "$current" = "$appendix" ]; then relative="${relative:-.}" echo "${relative#/}" return 0 fi current="${current%/*}" relative="$relative${relative:+/}.." done relative="$relative${relative:+${appendix:+/}}${appendix#/}" echo "$relative" } relpath "$@" -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org
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