ls: set default quoting style to literal when not TTY

[RenjiSann]

This PR fixes the quoting behavior of ls when stdout is non-TTY.
Until now, Coreutils' ls used the same default quoting style no matter what. However, GNU ls uses shell escaped quoting when stdout is a TTY, and Literal quoting otherwise.

I had to modify some quoting tests which expected the TTY-flavored output.

In the future, we should test that the output is still correct when running in the terminal by emulating an stdout file descriptor that can fake the is_terminal() behavior.

Fixes #5490

[RenjiSann]

I have no Windows machine on which I can test the actual output of ls in a non-TTY, so I don't know if I should fix the tests or add another condition for the default quoting style depending on the host OS.

Can someone verify the GNU ls behavior on Windows ?

[allaboutevemirolive]

I have no Windows machine on which I can test the actual output of ls in a non-TTY, so I don't know if I should fix the tests or add another condition for the default quoting style depending on the host OS.

Can someone verify the GNU ls behavior on Windows ?

After finishing my work today, I'll test this

[RenjiSann]

@allaboutevemirolive Any update ? 😁

[tertsdiepraam]

Nice! I think this is good enough to be merged, apart from the tests. I think we can assume that Windows will work the same way, so if you can adapt the tests on Windows accordingly (see the CI output) then it should be fine!

If you want a next challenge (for another PR). Here's what the GNU docs say:

You can specify the default value of the --quoting-style option with the environment variable QUOTING_STYLE. If that environment variable is not set, the default value is ‘shell-escape’ when the output is a terminal, and ‘literal’ otherwise.

We don't support that environment variable yet either :)

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/tail/inotify-dir-recreate is no longer failing!

[RenjiSann]

I've updated the windows tests !

If you want a next challenge (for another PR). Here's what the GNU docs say:

You can specify the default value of the --quoting-style option with the environment variable QUOTING_STYLE. If that environment variable is not set, the default value is ‘shell-escape’ when the output is a terminal, and ‘literal’ otherwise.

May I have the link to this ?

[cakebaker]

@RenjiSann https://www.gnu.org/software/coreutils/manual/html_node/Formatting-the-file-names.html

[cakebaker]

Thanks for your PR :)