Tig: Doesn't work command with pipe in zsh

[seiyeah78]

When use tig command with pipe | in zsh, command stop every time.

$ git log | tig
zsh: done                    git log |
zsh: suspended (tty output)  tig

$ fg
[1]  + done       git log |
       continued  tig
zsh: can't set tty pgrp: operation not permitted

What's the problem?

[koutcher]

You don't give much information on your configuration but some zsh versions had a regression on pgrp.

[2energycell]

I have the similar issue, the command git diff head|tig returns:

[1]  + 1026 done                    git diff head |
          1027 suspended (tty output)  tig

instead of showing what is expected.
I have all the newest: catalina, zsh, ohmyzsh, iterm2, brew, etc;
@jonas please help

[koutcher]

The problem is linked with calls to setpgid / tcsetpgrp that were introduced by 71e8361.

The command fails with zsh 5.7.1 (x86_64-apple-darwin15.6.0) and zsh 5.6 (x86_64-apple-darwin15.6.0), however it worked well with zsh 5.0.8 (x86_64-apple-darwin15.0) and zsh 5.5.1 (x86_64-apple-darwin15.6.0) and it also works with other shells like ksh, bash.

So the cause is likely to be a regression in zsh introduced between zsh 5.5.1 and 5.6:

2018-04-17  Peter Stephenson  <[email protected]>

    * 42630: Src/exec.c, Src/signals.c: Improve process group
    handling in pipelines.  Main shell will reclaim terminal if
    leader exits.  Allow SIGCHLD to interrupt reading data from
    command substitution. 

[lwfitzgerald]

I quick way to install zsh 5.5.1 for those using homebrew:

HOMEBREW_NO_AUTO_UPDATE=1 brew install https://raw.githubusercontent.com/Homebrew/homebrew-core/6d3232544b5f6f0d2b65c6ed89622beb11c4643b/Formula/zsh.rb

Catalina isn't in the formula at this point.

[koutcher]

If you don't want to downgrade zsh, the workaround is to use parentheses: git log | (tig).

[seiyeah78]

@koutcher @lwfitzgerald
Thank you for your reply and suggesting a solution!

@2energycell
I added alias to .zshrc like this.

alias tig=\(tig\)

git diff head | tig means git diff head | (tig) and work correctly.

[nedbat]

The parenthesis trick isn't working for me, using zsh 5.8. Any other ideas to make it work?