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How can I see what applications are making my shell commands slow?

Recently I had noticed that some shell commands on my laptop were executing surprisingly slow.

Like most things in the tech world, it was due to a piece of jamf software locking up anything that was being read.

I managed to validate this assumption using the command fs_usage which requires sudo. Here’s an example of it in action.

> sudo fs_usage | grep zshrc
Password:
16:19:22  open              /Users/marcus/dotfiles/zsh/zshrc.md                                              0.000021   lugh
16:19:22  open              /Users/marcus/dotfiles/zsh/.zshrc                                                0.000137   lugh
16:19:22    WrData[A]       /Users/marcus/dotfiles/zsh/.zshrc                                                0.000324 W lugh
16:19:22  lstat64           /System/Volumes/Data/Users/marcus/dotfiles/zsh/.zshrc                            0.000015   fseventsd
16:19:22  lstat64           dotfiles/zsh/.zshrc                                                              0.000005   perl5.28
16:19:22  lstat64           .zshrc                                                                           0.000007   perl5.28
16:19:22  lstat64           .zshrc                                                                           0.000004   perl5.28
16:19:22  readlink          .zshrc                                                                           0.000004   perl5.28
16:19:22  stat64            dotfiles/zsh/.zshrc/.stow                                                        0.000002   perl5.28
16:19:22  stat64            dotfiles/zsh/.zshrc/.nonstow                                                     0.000001   perl5.28
16:19:22  stat64            dotfiles/zsh/.zshrc                                                              0.000004   perl5.28
16:19:22  fsgetpath         /Users/marcus/dotfiles/zsh/.zshrc                                                0.000005   Finder
16:19:22  getattrlist       /Users/marcus/dotfiles/zsh/.zshrc                                                0.000014   Finder
16:19:22  fsgetpath         /Users/marcus/dotfiles/zsh/.zshrc                                                0.000005   Finder
16:19:22  fsgetpath         /Users/marcus/dotfiles/zsh/zshrc.md                                              0.000005   Finder
16:19:22  getattrlist       /Users/marcus/dotfiles/zsh/zshrc.md                                              0.000012   Finder
16:19:22  fsgetpath         /Users/marcus/.zshrc                                                             0.000005   Finder
16:19:22  getattrlist       /Users/marcus/.zshrc                                                             0.000015   Finder
16:19:22  fsgetpath         /Users/marcus/zshrc.md                                                           0.000005   Finder
16:19:22  getattrlist       /Users/marcus/zshrc.md                                                           0.000014   Finder
16:19:22  fsgetpath         /Users/marcus/zshrc.md                                                           0.000003   Finder
16:19:22  getxattr          dotfiles/zsh/zshrc.md                                                            0.000014   Finder
16:19:22  fsgetpath         /Users/marcus/zshrc.md                                                           0.000004   Finder
16:19:22  fsgetpath         /Users/marcus/zshrc.md                                                           0.000003   Finder
16:19:23  lstat64           /System/Volumes/Data/Users/marcus/dotfiles/zsh/.zshrc                            0.000005   fseventsd

Now this output doesn’t actually come from my work computer so you won’t see the mentioned JamfAgent but we can walk through this anyway.

First is lugh, a custom and possibly temporary literate markdown tool I use on my dotfiles. Next is perl, in the form of GNU Stow followed by macOS Finder doing some things. This gives a really nice breakdown of what is going on.

You can even use it to better understand applications, like if you run git status and see all the files that were touched within the .git folder.

I actually spotted that Yet Another Daemon was touching some of my .git files on my work laptop too. Shoo!