failing to source virtualenvwrapper on alpine linux (ash)

[agowa]

Hi, currently the virtualenvwrapper.sh script fails to be sourced on alpine linux.

This line of code

virtualenvwrapper/virtualenvwrapper.sh

Line 106 in c0f5193

export VIRTUALENVWRAPPER_SCRIPT="${.sh.file}"

currently causes -ash: /usr/bin/virtualenvwrapper.sh: line 109: syntax error: bad substitution when using the ash shell on alpine linux.

[agowa]

May be the same issue as with fish shell however I've not tried it there. Just guessing from the surrounding code.
#100

[ferdnyc]

${.sh.file} is ksh syntax, but ksh support was dropped in commit d736549 so that branch probably should've been taken out too.

That still won't help your shell, though, because without a default VIRTUALENVWRAPPER_SCRIPT won't get set.

Really, using $0 should probably be the default -- that will even work in Bash, under most cases, although $BASH_SOURCE is certainly better if it's available.

[ferdnyc]

Although, interestingly, when sourcing a script it seems that $0 is the ONLY thing that works for Zsh, and $BASH_SOURCE is the only thing that works for Bash.

so I guess the first question is, if you save this script to a file test_arg0.sh:

echo "0: $0"
echo "BASH_SOURCE: ${BASH_SOURCE}"
echo "ZSH_ARGZERO: ${ZSH_ARGZERO}"
echo "ZSH_SCRIPT: ${ZSH_SCRIPT}"

# Feel free to add any additional variables
# your shell's documentation indicates might be useful.

Then what do you get in ash for each of these scenarios?

1. (At any shell prompt):

   ash test_arg0.sh

2. (At an ash shell prompt):

   source test_arg0.sh

Here's what I get

Zsh

$ zsh test_arg0.sh
0: test_arg0.sh
BASH_SOURCE: 
ZSH_ARGZERO: test_arg0.sh
ZSH_SCRIPT: test_arg0.sh

$ source test_arg0.sh
0: test_arg0.sh
BASH_SOURCE: 
ZSH_ARGZERO: zsh
ZSH_SCRIPT: 

Bash

$ bash test_arg0.sh 
0: test_arg0.sh
BASH_SOURCE: test_arg0.sh
ZSH_ARGZERO: 
ZSH_SCRIPT: 

$ source test_arg0.sh 
0: bash
BASH_SOURCE: test_arg0.sh
ZSH_ARGZERO: 
ZSH_SCRIPT: 

[ferdnyc]

May be the same issue as with fish shell however I've not tried it there. Just guessing from the surrounding code.
#100

I don't think fish is ever gonna work. It dumps out with an error anytime a variable reference uses curly braces! (What are they THINKING??)

$  source test_arg0.sh
test_arg0.sh (line 2): Variables cannot be bracketed. In fish, please use "$BASH_SOURCE".
echo "BASH_SOURCE: ${BASH_SOURCE}"

[dhellmann]

I think there's an alternative implementation for fish.

I've never heard of the ash shell. If its syntax can be supported without breaking anything, I could review patches.

[ferdnyc]

@DHELLMAN See #117, though I don't know whether that's a complete solution. It at least gives ash and others like it a fighting chance, by no longer defaulting to KSH syntax for all shells that aren't Bash or Zsh.

[ferdnyc]

I just remembered that alpine publishes docker containers, which makes it really easy to test the ash shell on a different system. So...

$ docker pull alpine:latest
$ docker run -t -i alpine:latest /bin/ash
/ # cat > test_arg0.sh
echo "0: $0"
echo "BASH_SOURCE: ${BASH_SOURCE}"
echo "ZSH_ARGZERO: ${ZSH_ARGZERO}"
echo "ZSH_SCRIPT: ${ZSH_SCRIPT}"
/ # source test_arg0.sh
0: /bin/ash
BASH_SOURCE: 
ZSH_ARGZERO: 
ZSH_SCRIPT: 

Conclusion: None of the existing methods will work for Ash. $0 shows us the wrong path. So we need to look for other supported options.

Looking at the man page, I don't see any documented method of determining the path where a sourced script is located. $0 is all it supports, and that remains the path to the shell binary.

[ferdnyc]

Ah, crap, that's my fault, I shouldn't have marked that PR as "fixes" this issue, since it doesn't.

...Thanks, you beat me to it.

[ferdnyc]

I've posted a StackExchange question asking how this might be solved.