Use /bin/sh and make mktemp use compatible with non-GNU

[probonopd]

Would it be possible to change #! /bin/bash to #! /bin/sh in all scripts that end up in the AppImages? This would improve compatibility, e.g., with FreeBSD, where /bin/bash does not exist (even if you install bash from Ports).

This line in apprun-hooks/linuxdeploy-plugin-gtk.sh breaks on FreeBSD and possibly on other systems:

CACHEDIR="$(mktemp --tmpdir --directory .AppRun.XXXXXXXX)"

If I change this for testing to

CACHEDIR=$(mktemp  -d  "/tmp/.AppRun.XXXXXXXX")

then the application runs.

The culprit is:

FreeBSD% mktemp --tmpdir --directory .AppRun.XXXXXXXX
mktemp: illegal option -- -
usage: mktemp [-d] [-q] [-t prefix] [-u] template ...
       mktemp [-d] [-q] [-u] -t prefix 

As per https://www.freebsd.org/cgi/man.cgi?mktemp, mktemp -d "/tmp/.AppRun.XXXXXXXX" works for me on FreeBSD but I have not tested it on Linux.

Reference:
geany/geany#1303

[TheTumultuousUnicornOfDarkness]

Hello @probonopd,

The shebang is set to /bin/bash because it is a Bash script actually.
Changing the Bourne shell dialect to POSIX implies adaptations in the whole script. As you already noticed, some commands and arguments needs to be updated.

ShellCheck is a good tool to help us with this. For instance:

$ shellcheck -s sh linuxdeploy-plugin-gtk.sh

In linuxdeploy-plugin-gtk.sh line 20:
    local variable="$1"
    ^------------^ SC3043: In POSIX sh, 'local' is undefined.


In linuxdeploy-plugin-gtk.sh line 21:
    local library="$2"
    ^-----------^ SC3043: In POSIX sh, 'local' is undefined.


In linuxdeploy-plugin-gtk.sh line 22:
    local default_path="$3"
    ^----------------^ SC3043: In POSIX sh, 'local' is undefined.


In linuxdeploy-plugin-gtk.sh line 37:
    local src=("${@:1:$#-1}")
    ^-------^ SC3043: In POSIX sh, 'local' is undefined.
              ^-------------^ SC3030: In POSIX sh, arrays are undefined.
                ^---------^ SC3057: In POSIX sh, string indexing is undefined.


In linuxdeploy-plugin-gtk.sh line 38:
    local dst="${*:$#}"
    ^-------^ SC3043: In POSIX sh, 'local' is undefined.
               ^-----^ SC3057: In POSIX sh, string indexing is undefined.


In linuxdeploy-plugin-gtk.sh line 40:
    for elem in "${src[@]}"; do
                 ^-------^ SC3054: In POSIX sh, array references are undefined.


In linuxdeploy-plugin-gtk.sh line 46:
    local tool="$1"
    ^--------^ SC3043: In POSIX sh, 'local' is undefined.


In linuxdeploy-plugin-gtk.sh line 47:
    local directory="$2"
    ^-------------^ SC3043: In POSIX sh, 'local' is undefined.


In linuxdeploy-plugin-gtk.sh line 53:
    PATH_ARRAY=(
               ^-- SC3030: In POSIX sh, arrays are undefined.


In linuxdeploy-plugin-gtk.sh line 61:
    for path in "${PATH_ARRAY[@]}"; do
                 ^--------------^ SC3054: In POSIX sh, array references are undefined.


In linuxdeploy-plugin-gtk.sh line 95:
if [ "$APPDIR" == "" ]; then
               ^-- SC3014: In POSIX sh, == in place of = is undefined.


In linuxdeploy-plugin-gtk.sh line 111:
if ! command -v patchelf &>/dev/null && ! type patchelf &>/dev/null; then
                         ^---------^ SC3020: In POSIX sh, &> is undefined.
                                                        ^---------^ SC3020: In POSIX sh, &> is undefined.


In linuxdeploy-plugin-gtk.sh line 112:
    echo -e "$0: patchelf not found.\nInstall patchelf then re-run the plugin."
         ^-- SC3037: In POSIX sh, echo flags are undefined.


In linuxdeploy-plugin-gtk.sh line 117:
    echo -e "$0: LINUXDEPLOY environment variable is not set.\nDownload a suitable linuxdeploy AppImage, set the environment variable and re-run the plugin."
         ^-- SC3037: In POSIX sh, echo flags are undefined.


In linuxdeploy-plugin-gtk.sh line 203:
FIND_ARRAY=(
           ^-- SC3030: In POSIX sh, arrays are undefined.


In linuxdeploy-plugin-gtk.sh line 212:
LIBRARIES=()
          ^-- SC3030: In POSIX sh, arrays are undefined.


In linuxdeploy-plugin-gtk.sh line 213:
for (( i=0; i<${#FIND_ARRAY[@]}; i+=2 )); do
^-^ SC3005: In POSIX sh, arithmetic for loops are undefined.


In linuxdeploy-plugin-gtk.sh line 214:
    directory=${FIND_ARRAY[i]}
              ^--------------^ SC3054: In POSIX sh, array references are undefined.


In linuxdeploy-plugin-gtk.sh line 215:
    library=${FIND_ARRAY[i+1]}
            ^----------------^ SC3054: In POSIX sh, array references are undefined.


In linuxdeploy-plugin-gtk.sh line 216:
    while IFS= read -r -d '' file; do
                       ^-- SC3045: In POSIX sh, read -d is undefined.


In linuxdeploy-plugin-gtk.sh line 217:
        LIBRARIES+=( "--library=$file" )
        ^-------^ SC3024: In POSIX sh, += is undefined.
                   ^-------------------^ SC3030: In POSIX sh, arrays are undefined.


In linuxdeploy-plugin-gtk.sh line 218:
    done < <(find "$directory" \( -type l -o -type f \) -name "$library" -print0)
           ^-- SC3001: In POSIX sh, process substitution is undefined.


In linuxdeploy-plugin-gtk.sh line 221:
env LINUXDEPLOY_PLUGIN_MODE=1 "$LINUXDEPLOY" --appdir="$APPDIR" "${LIBRARIES[@]}"
                                                                 ^-------------^ SC3054: In POSIX sh, array references are undefined.


In linuxdeploy-plugin-gtk.sh line 224:
PATCH_ARRAY=(
            ^-- SC3030: In POSIX sh, arrays are undefined.


In linuxdeploy-plugin-gtk.sh line 229:
for directory in "${PATCH_ARRAY[@]}"; do
                  ^---------------^ SC3054: In POSIX sh, array references are undefined.


In linuxdeploy-plugin-gtk.sh line 230:
    while IFS= read -r -d '' file; do
                       ^-- SC3045: In POSIX sh, read -d is undefined.


In linuxdeploy-plugin-gtk.sh line 233:
    done < <(find "$directory" -name '*.so' -print0)
           ^-- SC3001: In POSIX sh, process substitution is undefined.

For more information:
  https://www.shellcheck.net/wiki/SC3001 -- In POSIX sh, process substitution...
  https://www.shellcheck.net/wiki/SC3005 -- In POSIX sh, arithmetic for loops...
  https://www.shellcheck.net/wiki/SC3014 -- In POSIX sh, == in place of = is ...

So, as you can see, not only the mktemp line must be changed... It is a huge rework.

[TheAssassin]

Since bash can be installed in FreeBSD but the location is not in /bin/bash, mind to tell where it is actually located? We can adapt the shebang.

Also, please check whether /usr/bin/env bash would work.

[probonopd]

Also, please check whether /usr/bin/env bash would work.

It exists if the user has installed the optional bash package. I still need to test whether it would work with this change.

[probonopd]

Running into this while trying to run xLights, too:

FreeBSD% mktemp --tmpdir --directory .AppRun.XXXXXXXX
mktemp: illegal option -- -
usage: mktemp [-d] [-q] [-t prefix] [-u] template ...
       mktemp [-d] [-q] [-u] -t prefix 

Changing the shebang to #!/usr/bin/env bash does not change this, presumably because mktemp is its own binary:

FreeBSD% ls -lh $(which mktemp)
-r-xr-xr-x  1 root  wheel   7,8K 24 Nov. 23:57 /usr/bin/mktemp

FreeBSD% file $(which mktemp)
/usr/bin/mktemp: ELF 64-bit LSB executable, x86-64, version 1 (FreeBSD), dynamically linked, interpreter /libexec/ld-elf.so.1, for FreeBSD 13.0 (1300139), FreeBSD-style, stripped

Looks like we could tackle this in two steps:

• Step 1: Make it work on non-GNU systems on which bash has been installed (by using #!/usr/bin/env bash and never #!/bin/bash, and by getting rid of mktemp or (if absolutely needed) using in a way that does not rely on GNU extensions and is compatible with https://www.freebsd.org/cgi/man.cgi?mktemp)
• Step 2: Make it work on non-GNU systems on which bash has not been installed (by converting bash scripts to POSIX shell scripts)

I hope that step 1 is way less work than step 2 @TheAssassin?

[TheTumultuousUnicornOfDarkness]

I agree we can use a POSIX mktemp, like you proposed:

mktemp -d "/tmp/.AppRun.XXXXXXXX"

Generally, I prefer to use long options because it is more human readable in scripts, but unfortunately they are mostly for GNU systems, and not POSIX compliant as you proven.

[TheAssassin]

Step 1 will likely work. Giving up on bash would be more than annoying, it's like using C89 instead of modern C++. I think it is acceptable to mandate bash to be available. The env trick I suggested earlier should work on all modern systems, it is way more widespread in the non-shell world (e.g., #! /usr/bin/env python, env is actually not part of POSIX but available everywhere allowing such patterns in those languages).

I don't think one wants to use, e.g., Python (needs to be shipped), or ship bash for such simple plugins. Making them run on non-Linux systems is fine, as long as it's just small adaptions which don't require changes in critical business logic etc.

Edit: by the way, I love shellcheck, it's such a huge help.

[TheAssassin]

Closed by #25. Thanks.