[BUG] Script hangs when awk is nawk

[AliShahabzadeh]

https://github.com/jgabaut/amboso/blob/9d68d2fb3e80a4bbb17b35a4b0b269c827904d1c/amboso_fn.sh#L1767

The program fails to proceed beyond this point on MacOS M1.

[jgabaut]

Darn, I was really hoping we could leave #58 behind. Sigh...

Let's look into this.

Can you remove the stderr suppression and see if it does anything? Delete 2>/dev/null and retry your check to ensure execution stops at that precise line.

These are set near the start of amboso_parse_args():

• target_awk should expand to awk
• bad_awk should expand to mawk

[AliShahabzadeh]

After removing the specified portion and executing the program, the subsequent line appeared in the output.

awk: unknown option -W ignored

[jgabaut]

That's a burn. I expected to be able to use -W to detect the actual version of the program symlinked to awk on a system, to differenciate between a full awk (we need some extensions) and mawk. If you look at this issue:

• 58

Near the bottom it says a version of mawk which was on another machine and also had problems. Can you try something like:

• awk --help to get which flags you have at your disposal
• awk --version to try to print your awk version. I don't know which syntax the flag should have.

[AliShahabzadeh]

When attempting the commands on a Mac M1, I observed that executing awk --help, awk --h, and awk -H did not yield any response. However, awk --version provided the output:

awk version 20200816

[jgabaut]

I'll try to look into this soon, I'm halfway through the release of invil 0.2.7 which ports the changes of 2.0.3. Should provide a patch for this and the included najlo bugs (see #99) in a couple of days.

Can you provide any more context about the problem? In particular:

• bash version you're using
• darwin version you're using (or which macOS release)
• More context about the awk you're rocking

I guess the "fix" is gonna end up being just checking for gawk directly and bailing when it's missing.

[jgabaut]

Apparently, the awk version provided by macOS only supports --version, while mawk only supports -W version.

See here for reference:

• https://github.com/exercism/awk/issues/123

The current check should be fixed and a correct guess should be made. I guess calling gawk directly may also work... I'll see.

[AliShahabzadeh]

Upon reviewing various developers' experiences, it became apparent to me that they resolved the issue by installing gawk. However, I remain uncertain whether MacOS utilizes a customized iteration of mawk under the guise of awk or employs an alternative version known as nawk.

[jgabaut]

@AliShahabzadeh We came to the same conclusion. Let me make some clarity:

• First of all, this issue related to the new awk script used to parse stego.lock was found:

  • 58

  • I did some testing on the machine (running Ubuntu) and I resorted to grepping the ouput of awk -W version, which was successful on both my machine and the mentioned one. Grepping for "mawk" in the output was to be used to determine if awk was actually mawk.

• I was assuming macOS was also shipping mawk.

• Apparently, that's not the case, as macOS is shipping the so-called one-true awk. We all bow in respect.

  • Reference this Wikipedia page: link

• The current issue is that nawk, mawk and gawk don't support a common syntax to print their version.

I updated the title to better distinguish this issue from the other, even though they come out of the same code section, since they have different reasons and a proper fix would necessarily mean handling both nawk and mawk properly. Hanging is not an option.

On a side note, I'm still confused at why the line mentioned in the first post (1767) just hangs. A guess:

• The awk call is being piped to grep, and the standard error is suppressed. But:
  • Your awk doesn't recognize -W, and quits with no output.
  • grep receives nothing and is stuck waiting for input

I'm not really sure if that's what's happening.

Now, onto fixing our issue:

Relying solely on the output grepping was a bad idea from the start, but for now we can just make the check sane (by trying both kind of version flags, checking the results of the command, and resolving which awk we have).

• [x] Add a method to properly check for awk implementation
• [x] Add handling of detected awk implementation
• [x] Changing the awk call to be explicitly for gawk for the stego.lock parsing script (the only problematic one, as 99% of the awk usage in our program is portable)
• [ ] Quitting with the wanted error when missing gawk
• [x] Updating README to add gawk to the list of dependencies

I would start working on this in a few days, but if you want to have a stab at it, please fork and branch with any changes you'd like to contribute. In any case, I should be able to chop this when I have a little time, it's not too hard.

[jgabaut]

@AliShahabzadeh my tests seem to show that the revised check in 2.0.4 should correctly pick up the needed gawk implementation for awk. Furthermore, I updated the README to better show that we actually need it.

Let me know if the new patch fixed your problem. Closed with the PR, for now.