Why is bash using single and double quotes literally?

Question

I have a situation in Bash I've never encountered before and don't know how to resolve. I installed bash on Alpine Linux (Docker Container) and for some reason environment variables with quotes translate literally.

MY_PATH="/home/my/path"

> cd $MY_PATH

Result

bash: cd: "/home/my/path": No such file or directory

> echo $MY_PATH

Result

"/home/my/path"

Now if you try it without quotes it works

MY_PATH=/home/my/path

> cd $MY_PATH

Result

bash-4.4# (path changed)

> echo $MY_PATH

Result

/home/my/path

I've never seen this before as I expect bash to gobble up the outer quotes, not even sure what to search for in trying to resolve this.

To fully qualify the scenario let me point out that:

Using Docker with an Alpine (3.8) image
Installing Bash 4 on Alpine that usually defaults to ash shell

Update

This is starting to look like a docker issue. I'm using the env_file in Docker Compose to push environment variables to a container and it looks like its literally copying quotes " => \".

Thanks to @bishop's comment to try od -x

container.env

#!/usr/bin/env bash
MY_PATH="/home/my/path"

Then inside the Alpine 3.8 container running env

MY_PATH="/home/my/path"

Update 2

Looks like there was a bug around this that was closed. But apparently doesn't seem fixed. Is it because I'm the only one in the universe still using Docker Toolbox?

Are you sure you used `"` as the double quotes, not `“` or `”`? — choroba, Aug 19 '18 at 18:34
`bash-4.4# echo $MY_PATH | od -x` `0000000 2f22 6f68 656d 6d2f 2f79 6170 6874 0a22 0000020` — qodeninja, Aug 19 '18 at 18:46
So when you're saying `MY_PATH="/home/my/path"`, you're not actually typing `MY_PATH="/home/my/path"` at the shell prompt? — melpomene, Aug 19 '18 at 18:49
@melpomene see my updated comments. Looks like Docker may be causing this. — qodeninja, Aug 19 '18 at 18:50

score 7 · Accepted Answer · answered Aug 19 '18 at 18:55

7

https://docs.docker.com/compose/env-file/

These syntax rules apply to the .env file:

Compose expects each line in an env file to be in VAR=VAL format.

Lines beginning with # are processed as comments and ignored.

Blank lines are ignored.

There is no special handling of quotation marks. This means that they are part of the VAL.

In particular, the env file is not a shell script and not seen by bash (your #!/usr/bin/env bash line is treated as a comment and ignored).

answered Aug 19 '18 at 18:55

melpomene

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Thanks I was just reading through that, looks like the real issue here is that literal translation of quotes is not (my) expected behavior. https://github.com/docker/compose/issues/3702 – qodeninja Aug 19 '18 at 19:02

Why is bash using single and double quotes literally?

1 Answers1