The chgrp command enables the user to change the group owner of a file or directory. The syntax is:
chgrp wheel Users
Here the directory Users is changed to be owned by the group wheel.
See Apple’s Mac OS X Manual Pages for further command details.
See my other CLI articles
The ln command allows you to make links in the filesystem. Specifically, it creates a local directory that points to the target file or directory. This allows you to
- have a file or directory be virtually present in multiple locations, yet only have one copy taking up space and requiring maintenance
- allow for content spread across multiple disk drives to appear as contiguous in the main drive.
The general use is with the -s option to specify a symbolic link. In the example below I create a symbolic link to the Pictures folder on the external drive D2, then show how it appears when the ls command is run.
Johns-Mac-mini:~ jpurvis$ sudo ln -s /Volumes/D2/Pictures Pictures
Johns-Mac-mini:~ jpurvis$ ls -l
drwx—— 3 jpurvis staff 102 Dec 28 14:32 Applications
drwxr-xr-x 71 jpurvis staff 2414 Feb 19 23:43 Calibre Library
drwx——+ 13 jpurvis staff 442 Mar 30 12:49 Desktop
drwx——+ 15 jpurvis staff 510 Mar 29 16:38 Documents
drwx——+ 88 jpurvis staff 2992 Mar 30 14:26 Downloads
drwx——@ 10 jpurvis staff 340 Nov 6 11:22 Dropbox
drwx——@ 8 jpurvis staff 272 Mar 23 18:40 Google Drive
drwx——+ 71 jpurvis staff 2414 Mar 6 09:24 Library
drwx——+ 12 jpurvis staff 408 Nov 6 09:54 Movies
drwx——+ 9 jpurvis staff 306 Dec 15 2008 Music
lrwxr-xr-x 1 root staff 20 Mar 30 14:45 Pictures -> /Volumes/D2/Pictures
The Apple Man page for the ln command can be seen here.
See my other CLI articles
A key tool to the System Administrator or the more advanced user of any Unix/Linux/OS X system is the Command Line Interface (CLI) and that is accessed on OS X systems through the Terminal App. Apple includes the Terminal App with the Utilities. To open the Terminal App got to Finder >> Go >> Utilities >> Terminal.
When the Terminal opens by default it will be at the Home directory for the user. Now the user can enter any commands into the terminal for execution.
If you want to adjust the font size used, you can do so by using the Command+Plus (+) key combination to increase the font size, or Command+Minus (-) to decrease the font size. Using Command-Zero (0) will return the font size to the default.
Through the Terminal Preferences you can also adjust the colors being used to find a background/foreground color combination to your liking. The example above is with the ‘Basic’ profile while the one below is using the ‘Homebrew’ profile.
I find that the ‘Homebrew’ profile provied more contrast and makes the Terminal content easier to read.
A simple ‘Terminal Cheatsheet for Mac‘ gives an over view of keyboard shortcuts for the Terminal App., as well as the most common CLI commands you might use.
See my other SysAdmin articles