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Sergey Kislyakov
Sergey Kislyakov

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Speed up macOS terminal

MacOS does ASL (Apple System Log) log lookup each time you open a tab in the terminal (you can confirm that by running sudo fs_usage | grep 'asl.*login' in a tab and open another one, clear buffer in the first one and open a new tab again to see it indeed does look up each time). There's a way to prevent that though. I'm not sure how important those logs are, the only thing that changed for me was "Last login" disappearance.

iTerm 2:

  1. Open Preferences - Profiles.
  2. Choose your profile (Default by default 😜).
  3. In the "General" tab, change Command from Login shell to /bin/bash (or any other *sh you're using).

You can confirm that iTerm does not lookup ASL logs anymore with sudo fs_usage | grep 'asl.*login' in one tab. Opening tabs should not show output that contain lines looking like private/var/log/asl/2020.01.12.U501.asl, though it may contain something like this:

17:58:04  stat64            /usr/lib/system/libsystem_asl.dylib                                              0.000008   login
17:58:04  stat64            /usr/lib/libsasl2.2.dylib                                                        0.000010   login
17:58:04  stat64            private/etc/asl/.noquota                                                         0.000024   login
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That's fine because it does not look up for private/var/log/asl.

A bit complicated this time.

  1. Create a symlink of your shell (e.g. /bin/bash) to /usr/local/bin/bash (e.g. ln -s /bin/bash /usr/local/bin/bash). You have to do that because will execute /usr/bin/login which does the ASL lookup if your shell is a default one (default shells are defined in /etc/shells, hence why we link it to /usr/local/bin, because shells in this folder are not defined in the file). Non-default shell will make execute /usr/bin/login -q, and -q skips ASL log look ups completely.
  2. Open Preferences - General.
  3. Change Shells open with to Command and put /usr/local/bin/bash there.
  4. Add -bash (or -zsh or -fish) to Profiles - Basic (Default) - Shell - Ask before closing. This will prevent popups like this when you're trying to close a tab:

Alt Text

You're done, confirm that you don't look up ASL logs using methods I described above.

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