macOS

How can I view configured networks in my terminal?

Let’s assume you have multiple networks set up under System Preferences > Networks.

You might have “Work” which has a bunch of proxy configuration specified and “Home” which just disabled proxy configuration.

If you left the former “Work” network selected, then went to a place that can’t access the proxy server, you wouldn’t be able to access the internet and vice versa.

To make automating this a little bit easier, there’s a command line tool called scselect

Here’s an example of what it looks like in action:

> scselect
Defined sets include: (* == current set)
 * <guid> (Work)
   <guid> (Home)

In this example, we can see the Work network is selected.

Now we wanted to change to the Home network, you could do so manually in System Preferences or you can run scselect with the name of the network you want to change to like so:

> scselect Home
CurrentSet updated to <guid> (Home)
> scselect
Defined sets include: (* == current set)
   <guid> (Work)
 * <guid> (Home)

As you can see, the Home network is now selected.

I only recently discovered this tool so I haven’t automated it yet but it’s probably feasible to have a file with your working hours and then if it’s within those hours, toggle on the Work network (and all of the proxy configuration that comes with it)

The reason you might want to use a schedule and not eg; WiFi name is that you might be working from home over a VPN for example.

How can I run a Homebrew application being blocked by Gatekeeper?

This issue is particularly annoying and I only just discovered it today for the first time.

Here’s an example of what it looks like

In order to install the application so that it bypasses Gatekeeper, you can rerun brew cask install like so:

> brew cask install --no-quarantine blah
> brew reinstall --no-quarantine blah

If you’d like to keep this flag enabled all the time, and honestly you might as well, you can also do the following:

> export HOMEBREW_CASK_OPTS="--no-quarantine"
> brew cask install blah

How can I hide folders in my Home directory?

If you’ve ever seen those pesky default folders like Public and Movies, the good news is that you can get rid of them.

You can’t, or more specifically, you shouldn’t fully delete them as some applications may assume their existence but you can get close enough.

Let’s say we want to hide Public, you can hide it from Finder like so:

chflags hidden ~/Public

The next time you navigate to your Home directory using Finder, you’ll see that they’ve magically disappeared

If you want to hide multiple at once, you can provide a comma delimited list:

chflags hidden ~/{Downloads,Public}

If, for whatever reason, you wanted to block anyone or anything from accessing those folders as well, you could use chmod to do that:

chmod 000 ~/{Downloads,Public}

Personally, I don’t bother with this step but you might have a use for it.

The one issue with the above is that you’ll see those files appear in your Terminal and I don’t know about you but that basically makes this whole exercise pointless.

There are ways to do it but I haven’t looked into them myself.

How can I see my route table?

For those of us who are subject to using corporate VPNs, all sorts of wackiness can occur such as 127.0.0.1 being routed first to another country before trying to resolve locally.

You can see both IPv4 and IPv6 routing entries by running netstat -rn. Personally, I like to just show IPv4 addresses.

Here’s an example of my route table with WiFi (and ethernet) interfaces disabled:

> netstat -nr -f inet
Routing tables

Internet:
Destination        Gateway            Flags        Netif Expire
127                127.0.0.1          UCS            lo0
127.0.0.1          127.0.0.1          UH             lo0
111.0.0            link#1             UmCS           lo0

I’ve changed the last entry since I don’t actually know if it’s an internet work address.

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!

How can I try out x-callback-url commands?

There is a CLI tool called xcall which seems to be the only way I’ve seen to actually interact with x-callback-url outside of other applications.

It’s a bit wonky in that you have to drag xcall.app to your Applications folder and then either add that to your path or reference the cli tool inside directly.

Here’s an example of it in use:

> /Applications/xcall.app/Contents/MacOS/xcall -url "things:///version" -activateApp NO
{
  "x-things-client-version" : "31310506",
  "x-things-scheme-version" : "2"
}

Annoyingly, this will activate the application in question, if it isn’t already open, but that is the nature of x-callback-url after all.

It will take the foreground view upon opening but further invocations won’t trigger it, assuming you use -activateApp NO. If you want it to appear, such as when triggering a search, you can use -activateApp YES instead.

How can I find out more about the hardware in my machine?

While there’s the classic Apple menu -> About This Mac -> System Report, a terminal based alternative is the system_profiler command.

You can use a list of queryable types like so:

> system_profiler -listDataTypes
Available Datatypes:
SPParallelATADataType
SPUniversalAccessDataType
[...]

Once you’ve found one or more types, you’re interested in then just append it after the command like so: system_profiler <type1> <type2>

Let’s see how it looks in action:

> system_profiler SPPowerDataType
Power:

    Battery Information:

      Model Information:
          Manufacturer: DSY
          Device Name: bq20z451
          Pack Lot Code: 0
          PCB Lot Code: 0
          Firmware Version: 1002
          Hardware Revision: 1
          Cell Revision: 2400
      Charge Information:
          Fully Charged: No
          Charging: Yes
          Full Charge Capacity (mAh): 4569
          State of Charge (%): 74
      Health Information:
          Cycle Count: 81
          Condition: Normal

This is just an excerpt of what is otherwise a whole bunch of information.

Particularly interesting is the SPAirPortDataType which can be queried to see a list of SSIDs in the environment.

How can I find out why my Mac has restarted?

This is arguably one of the more obscure commands I’ve come across. At the time, a coworker of mine was having issues where his laptop would restart seemingly at random.

We were able to find out a bit more with the following command:

log show -predicate 'eventMessage contains "Previous shutdown cause"' -last 24h

It may take a minute or so to actually find some logs but it should reveal a shutdown code.

I don’t remember where I dug it up but you can see a list of shutdown causes and their meanings in this PDF.

Here’s how the results looks on my machine where I had performed a normal shutdown as a test

If we compare the shutdown code to the PDF above, we can see the description is Correct shut down which lines up exactly.

Now let’s take this information and use it to see what was potentially happening to my coworkers laptop.

Here’s a screenshot of his terminal window with the same command:

Going back to the PDF again, we can see that -128 is an alias for -112. Checking -112 tells us that it is “Probably memory related” which at least narrows it down.

I won’t know it since some of the most authoritative information can often be found in PDF randomly floating around the internet and it’s better than nothing!

For anyone wonder, my coworker has a new laptop on the way regardless since he can’t work with it constantly rebooting.

How can I use my clipboard contents in my terminal?

I’ve known about this tool for some time now but I’m writing about it because I ALWAYS forget to use it.

pbcopy, and as I just discovered, pbpaste are two tools that are built into macOS.

You can pipe data into the former to add it to your clipboard and similarly, you can use the latter as input into a unix pipeline.

Let’s look at an example:

> echo "see you on the other side" | pbcopy

You can now use Ctrl+V to paste this text into any GUI application. Saves you having to mouse over to the terminal and highlight text but I still do it every darn time.

We can also use our clipboard contents too as mentioned. You could have copied some text from a GUI application and you want to use it in your terminal.

# Clipboard contains "utf9k.net" that I copied from my browser
> pbpaste | xargs dig TXT | grep "I see"
utf9k.net.		3444	IN	TXT	"I see you snoopin' around ;) If you're after something, you can feel fr\010ee to email me at marcus@utf9k.net"

What I’m trying to say is that I have all of the tools at my disposal to avoid RSI but I just need to remember they exist…