bat silently quits, rather than reporting an error, if less is missing

[FlashSheridan]

What steps will reproduce the bug?

1. Install bat on a machine without less (a minimal Docker image in my case with 22.04.4 LTS (Jammy Jellyfish) x86_64, where of course bat was the first thing I wanted to install):
   sudo apt install bat fd-find…
2. Run it:

batcat  --generate-config-file
batcat  /root/.config/bat/config

What happens?
Nothing, but the file exists:

root@kromodeor:~/Documents/Code/compiler-tester/llvm# batcat  /root/.config/bat/config
root@kromodeor:~/Documents/Code/compiler-tester/llvm# ls -l  /root/.config/bat/config
-rw-r--r-- 1 root root 1114 Mar 19 15:58 /root/.config/bat/config

What did you expect to happen instead?

Error message stating that my poor pathetic installation lacked less.

How did you install bat?

time sudo apt install bat fd-find silversearcher-ag tldr  nano

---

bat version and environment

batcat /root/.config/bat/config --diagnostic
bat has been built without the 'bugreport' feature. The '--diagnostic' option is not available.

batcat --version
bat 0.19.0

apt info bat
Package: bat
Version: 0.19.0-1ubuntu0.1
Built-Using: rust-ansi-colours (= 1.0.1-2), rustc (= 1.59.0+dfsg1-1~ubuntu2~22.04.1)
…

[Muresan73]

I would look into this, can you assign it to me please.

[Muresan73]

In the meantime, I tried to reproduce the issue, but I could not replicate the same behavior as @FlashSheridan .
Using the ubuntu:jammy container, I verified that less is not present, and then running your command resulted in:

root@test:/# less
bash: less: command not found

root@test:/# batcat  -V                      
bat 0.19.0

root@test:/# batcat  --generate-config-file
Success! Config file written to /root/.config/bat/config

root@test:/# batcat  /root/.config/bat/config
       │ File: /root/.config/bat/config
───────┼────────────
   1   │ # This is `bat`s configuration file. Each line either contains a comment or
   2   │ # a command-line option that you want to pass to `bat` by default. You can
   3   │ # run `bat --help` to get a list of all possible configuration options.
   4   │ 
   5   │ # Specify desired highlighting theme (e.g. "TwoDark"). Run `bat --list-themes`
   6   │ # for a list of all available themes
   7   │ #--theme="TwoDark"
...

In my case, bat defaults correctly to not using a pager if less is not present.

Could it be that somehow no argument is received, causing bat to hang and wait for stdin as it normally does?

[FlashSheridan]

(a minimal Docker image in my case with 22.04.4 LTS (Jammy Jellyfish) x86_64,

In the meantime, I tried to reproduce the issue, but I could not replicate the same behavior as @FlashSheridan . Using the ubuntu:jammy container, …

Hmm, there could well be something else unusual about our company’s minimal Docker image. Attached is the relevant part of the session in which I created the container and encountered the problem. We’re in the process of open-sourcing; let me know if there’s anything you can’t access, or if you need more information.

Docker cmds excerpts 2024-03-20 6-39-09 PM.txt

[Muresan73]

I used your image, tried to have different permissions for less, played around with bat config but the results were the same.

I will try to tamper the code maybe something pops up.

[FlashSheridan]

I used your image, tried to have different permissions for less, played around with bat config but the results were the same.

Odd, on my container the bug reproduced when I removed less, below. Happy to run diagnostics while it’s in this state.

root@kromodeor:/# apt remove less
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following packages will be REMOVED:
  less
0 upgraded, 0 newly installed, 1 to remove and 6 not upgraded.
After this operation, 329 kB disk space will be freed.
Do you want to continue? [Y/n] y
(Reading database ... 42244 files and directories currently installed.)
Removing less (590-1ubuntu0.22.04.2) ...
Processing triggers for mailcap (3.70+nmu1ubuntu1) ...
root@kromodeor:/# 
root@kromodeor:/# 
root@kromodeor:/# batcat  /root/.config/bat/config

This is a pretty minimal image, e.g.

root@kromodeor:/# man apt
This system has been minimized by removing packages and content that are
not required on a system that users do not log into.

To restore this content, including manpages, you can run the 'unminimize'
command. You will still need to ensure the 'man-db' package is installed.

[Muresan73]

I was checking the code, and bat should fall back to regular non-pager stdout if the pager initiation have any problems. I couldn't find any corner cases.
On the other hand, if the pager itself encounters any problems that is outside of bat's scope. My guess is there is maybe a misconfigured less binary or symlink on your path that outputs nothing for some reason. I created a dummy binary, and the output is piped through it.

root@46test:/# batcat  /root/.config/bat/config --pager=lesser 
Hello, world!
thread 'main' panicked at src/main.rs:3:5:
There was an issue                                                                                           

[FlashSheridan]

Interesting, I get the usual silent failure with a nonexistent pager:

root@kromodeor:/# batcat  /root/.config/bat/config   --pager=SirNotAppearingInThisContainer
root@kromodeor:/# echo $?
0