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Terminal

How to auto-crop huge images with ImageMagick

Rob Griffiths
May 22 '19
[Mac OS X Hints, Terminal, Unix]
Comments

In my recent post A new set of Hubble deep space iMac retina desktops, I included a set of auto-cropped 5120x2880 desktops. In that post, I wrote:

These images were automatically cropped from the master image (after I cropped that; more detail on what I did is coming in a follow-up post), via ImageMagick.

So this would be that post: How to auto-crop huge images using ImageMagick. If you're not familiar with it, ImageMagick is a set of command-line tools to manipulate images. There are a number of ways to install ImageMagick, but I used Homebrew (brew install imagemagick).

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2019 iMac vs Late 2014 iMac—Ripping addendum

Rob Griffiths
Apr 30 '19
[Apple, Blu-ray/DVD Ripping, Cool Hardware, Macs, Terminal]
2 Comments

In Part 1 of my 2014 vs 2019 iMac comparison articles, I provided an overview and a number of comparison benchmark results. In Part 2, I looked at changes in gaming performance between the two machines.

But there was one more thing I wanted to do: Compare Blu-ray ripping speeds. At the time, though, I didn't have any new movies to rip, and I really didn't want to spend the time re-ripping an existing movie. Now, though, I do have a few new movies to rip, as I'm trying to finish our collection of all the films in the first three phases (now called the Infinity Saga) of the Marvel Cinematic Universe.

That meant buying the films I'd liked the least—The Incredible Hulk and the first two Thor movies. With that came the chance to compare the Blu-ray ripping speed of the two iMacs. I use the method described in my article Revisiting ripping Blu-ray discs, which is this:

  1. Use MakeMKV to create an MKV file on the hard drive that contains the video and audio tracks.
  2. Use Don Melton's Video Transcoding tools to create the final movie from the MKV file.

Using The Incredible Hulk, I timed how long it took to create the MKV file and how long it took to create the finished movie. Without further ado, the results (times are in hh:mm:ss format)…

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Using command-line Quick Look as a memory aid

Rob Griffiths
Apr 29 '19
[Mac OS X Hints, macOS, Terminal]
Comments

I recently reviewed my new third-party mouse, the Logitech MX Master 2s ($70 at Amazon). I love all the customizable buttons on this mouse, and in particular, the ability to create gestures (which are simply a directional drag while holding down a button).

I've used two buttons to create a total of 10 gesture actions on my mouse:

I created the above image from the Logitech Options app, so I can refer to it if I forget which action I've assigned to which gesture. But it's a pain to find the folder on the disk and open it just to see the image. Then I remembered I had an unused button on my mouse1The upper button of the two near the side scroll wheel…

Note: While the following is specific to my Logitech mouse in terms of implementation, read on if you're curious about how to access QuickLook previews from Terminal and/or via a simple AppleScript.

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Easily see any app’s bundle identifier

Rob Griffiths
Jun 12 '18
[Mac OS X Hints, Terminal, Unix]
1 Comment

I occasionally need to help one of our customers get the bundle identifier for a given app, for some purpose with one of our apps. While the task isn't complicated—the value is stored in a file named Info.plist within each app bundle—it's not something that's necessarily easy to explain to someone who doesn't have a lot of Mac experience.

I figured there must be a less-complicated solution, and I was right, though it's probably higher on the geek factor. After some searching, I found this thread at Super User, which offers a number of solutions. The simplest—and always working, in my experience—was the very first one: Open Terminal and run this command:

osascript -e 'id of app "Name of App"'

The "Name of App" is replaced with the name of the app as it appears when hovering over its Dock icon. For Excel, for example, it'd be:

osascript -e 'id of app "Microsoft Excel"'

Run that command, and it returns com.microsoft.Excel, which is just what I need—I just have the customer copy the output and email it back to me.

View app-specific log messages in Terminal

Rob Griffiths
Mar 30 '18
[Mac OS X Hints, macOS, Terminal]
1 Comment

March 29 2018 Update:

When this tip was first posted, it didn't work right: The log command ignored the --start, --end, and --last parameters. Regardless of what you listed for parameters, you'd always get the entire contents of the log file. I'm happy to note that this has been resolved in macOS 10.13.4, as log now functions as expected:

$ log show --last 20s --predicate 'processImagePath CONTAINS[c] "Twitter"'
Filtering the log data using "processImagePath CONTAINS[c] "Twitter""
Skipping info and debug messages, pass --info and/or --debug to include.
Timestamp                       Thread     Type        Activity             PID    TTL  
2018-03-30 09:26:15.357714-0700 0xc88a8    Default     0x0                  5075   0    Twitterrific: (CFNetwork) Task <9AD0920A-7AE7-4313-A727-6D34F4BBE38F>.<250> now using Connection 142
2018-03-30 09:26:15.357742-0700 0xc8d7a    Default     0x0                  5075   0    Twitterrific: (CFNetwork) Task <9AD0920A-7AE7-4313-A727-6D34F4BBE38F>.<250> sent request, body N
2018-03-30 09:26:15.420242-0700 0xc88a8    Default     0x0                  5075   0    Twitterrific: (CFNetwork) Task <9AD0920A-7AE7-4313-A727-6D34F4BBE38F>.<250> received response, status 200 content K
2018-03-30 09:26:15.420406-0700 0xc8d7a    Default     0x0                  5075   0    Twitterrific: (CFNetwork) Task <9AD0920A-7AE7-4313-A727-6D34F4BBE38F>.<250> response ended
 --------------------------------------------------------------------------------------------------------------------
Log      - Default:          4, Info:                0, Debug:             0, Error:          0, Fault:          0
Activity - Create:           0, Transition:          0, Actions:           0
$

This makes it really easy to get just the time slice you need from the overly-long log files. You can use s for seconds, m for minutes, h for hours, and d for days as arguments to these parameters.

This article provides a nice overview on interacting with log and predicates to filter the output—there's a lot you can do to help figure out what might be causing a problem.

And now, here's the rest of the original post…

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See how long an app has been running

Rob Griffiths
Sep 19 '17
[Mac OS X Hints, Terminal, Unix]
2 Comments

For a recent customer support question, I needed to know how long our app Witch had been running. There are probably many ways to find this out, but I couldn't think of one. A quick web search found the solution, via ps and the etime flag.

You need the process ID (pid), which you can find via ps ax | grep [a]ppname.1That [s]quare brackets around the first letter are there so grep won't find itself—and thus list itself in the output. In my case, Witch runs a background task called witchdaemon, so I did it this way…

$ ps -ax | grep [w]itchd
  774 ??        26:40.73 /Users/robg/Library/PreferencePanes...[trimmed]

With the pid, the command to find that process' uptime is:

$ ps -o etime= -p "774"
11-03:17:12

The elapsed time readout is in the form of dd-hh:mm:ss, so Witch had been running for 11 days and a few hours and minutes. Note that you can combine these steps, getting the process ID and using it in the ps command all at once:

ps -o etime= -p "`ps -ax | grep [a]ppname | cut -d ' ' -f 1`"

It's messy looking, but this form saves time and typing.

June 2018 Addendum: If you add the lstart flag, you can see the exact start date and time for the process. For example:

$ ps -o lstart= -o etime= -p "16866"
Tue Jun  5 05:49:19 2018     09-06:11:25

Selective pruning of old rsync backups

Rob Griffiths
May 2 '17
[Mac OS X Hints, Terminal, Unix]
1 Comment

In yesterday's post, I described a couple rsync oddities, and how they'd led me to this modified command for pruning old (older than four days) backups:

find /path/to/backups/ -d 1 -type d -Bmin +$((60*4*24)) -maxdepth 1 -exec rm -r {} +

After getting this working, though, I wondered if it'd be possible to keep my backups from the first day of each month, even while clearing out the other dates. After some digging in the rsync man page, and testing in Terminal, it appears it's possible, with some help from regex.

My backup folders are named with a trailing date and time stamp, like this:

back-2017-05-01_2230
back-2017-05-02_0534
back-2017-05-02_1002

To keep any backups made on the first of any month, for my folder naming schema, the modified find command would look like this:

find /path/to/backups/ -d 1 -type d -Bmin +$((60*4*24)) -maxdepth 1 -not -regex ".*-01_.*" -exec rm -r {} +

The new bits, -not -regex ".*-01_.*" basically say "find only files that do not contain anything surrounding a string that is 'hyphen 01 underscore.' And because only backups made on the first of the month will contain that pattern, they're the only ones that will be left out of the purge.

This may be of interest to maybe two people out there; I'm documenting it so I remember how it works!

How to not accidentally delete all your rsync backups

Rob Griffiths
May 1 '17
[Mac OS X Hints, Terminal, Unix]
7 Comments

With my Time Machine-like rsync backups running well, I decided it was time to migrate over the cleanup portion of my old script—namely, the bit that removes older backups. Soon after I added this bit to my new script, though, I had a surprise: All of my backups, save the most recent, vanished.

In investigating why this happened, I stumbled across two rsync/macOS behaviors that I wasn't aware of…and if you're using rsync for backup, they may be of interest to you, too.

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How to burn an ISO file to a USB stick

Rob Griffiths
Apr 27 '17
[Mac OS X Hints, macOS, Terminal, Unix]
1 Comment

I wanted to install Linux on a hard drive in Frankenmac, as Clover is a multi-boot utility—it lets you choose from any OS it sees during power up. (I'll add Windows, too, eventually.) To do this, you need to get Linux onto a USB stick. I've done this in the past, and my vague recollection of the process was download the ISO, convert to an image file, write image file to USB stick. However, as it'd been a few years, I went searching for references to make sure I had all the commands correct.

I found a lot of pages with a general summary of the process, and few with the specific steps. I tried one of those, but my USB stick didn't work. The other specific pages contained the same basic process, so I was stuck. Until I found this page, which contained a critical step I was missing: Formatting the USB stick before copying the image file.

For future reference, here's the precise process to follow if you want to burn an ISO file onto a USB stick…

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How to install ruby gems in Terminal

Rob Griffiths
Apr 26 '17
[Mac OS X Hints, Terminal, Unix]
3 Comments

In yesterday's tip, See sensor stats in Terminal, I implied that installation of the iStats ruby gem was a simple one-line command. As a commenter pointed out, that's only true if you already have the prerequisites installed. The prerequisites in this case are the Xcode command line tools. Thankfully, you can install those without installing the full 5GB Xcode development environment.

(Rather than starting from scratch, I'm just going to borrow this bit from my detailed instructions for installing the transcode-video tools, because the Xcode command line tools are required there, too.)

Here's how to install the command line tools. Open Terminal, paste the following line, and press Return:

xcode-select --install

When you hit Return, you'll see a single line in response to your command:

$ xcode-select --install
xcode-select: note: install requested for command line developer tools

At this point, macOS will pop up a dialog, which is somewhat surprising as you're working in the decidedly non-GUI Terminal:

Do not click Get Xcode, unless you want to wait while 5GB of data downloads and installs on your Mac. Instead, click the Install button, which will display an onscreen license agreement. Click Agree, then let the install finish—it'll only take a couple of minutes.

If you're curious as to what just happened, the installer created a folder structure in the top-level Library folder (/Library > Developer > CommandLineTools), and installed a slew of programs in the usr folder within the CommandLineTools folder.

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