gst-launch-1.0 prints printf usage on run

[nh2]

Issue description

On Ubuntu:

NIX_PATH=nixpkgs=https://github.com/NixOS/nixpkgs/archive/426028047db79f1ec567a0f60dcebc0b8ef1ddab.tar.gz nix-shell -p gst_all_1.gstreamer --run 'gst-launch-1.0 --version'
printf: usage: printf [-v var] format [arguments]
gst-launch-1.0 version 1.16.0
GStreamer 1.16.0
Unknown package origin

Why printf: usage: printf [-v var] format [arguments]?

It seems the wrapper is wrong somehow.

Contents:

#! /nix/store/w9ngash2dw3pvl98ysd79qy2rkkmc8my-bash-4.4-p23/bin/bash -e
export GST_PLUGIN_SYSTEM_PATH=$GST_PLUGIN_SYSTEM_PATH${GST_PLUGIN_SYSTEM_PATH:+:}$(unset _tmp; for profile in $NIX_PROFILES; do _tmp=$profile/lib/gstreamer-1.0${_tmp:+:}$_tmp; done; printf $_tmp)
exec -a "$0" "/nix/store/l94mb3cy5scyxvrhn04039l2yn183zbb-gstreamer-1.16.0-dev/bin/.gst-launch-1.0-wrapped"  "${extraFlagsArray[@]}" "$@"

Perhaps in printf $_tmp, $_tmp doesn't exist?

$ bash -x /nix/store/l94mb3cy5scyxvrhn04039l2yn183zbb-gstreamer-1.16.0-dev/bin/gst-launch-1.0 
++ unset _tmp
++ printf
printf: usage: printf [-v var] format [arguments]
+ export GST_PLUGIN_SYSTEM_PATH=
+ GST_PLUGIN_SYSTEM_PATH=
+ exec -a /nix/store/l94mb3cy5scyxvrhn04039l2yn183zbb-gstreamer-1.16.0-dev/bin/gst-launch-1.0 /nix/store/l94mb3cy5scyxvrhn04039l2yn183zbb-gstreamer-1.16.0-dev/bin/.gst-launch-1.0-wrapped

CC @jtojnar

[nh2]

I have no $NIX_PROFILES btw.

[jtojnar]

We have to use NIX_PROFILES for the same reason as here: #33277 (comment)

Not really sure what to do about non-NixOS. Perhaps make the setting of the path conditional on the presence of NIX_PROFILES variable and rely on user having to set the variable manually? How else would GStreamer find plugins when there is no global /usr? Unless we want to use the plugins installed with apt, but I am not sure our GStreamer will support that since it was compiled with --prefix=$out not --prefix=/usr.

[jtojnar]

printf "$_tmp" might be a suitable fix for now.

[bjornfor]

I always thought that nix shell setup code on non-NixOS should set NIX_PROFILES=$HOME/.nix-profile, but never got around to submitting a PR.

[lheckemann]

Also, it should probably be printf %s "$_tmp" instead?

[stale]

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