TweetFollow Us on Twitter

Easing Into dscl

Volume Number: 22 (2006)
Issue Number: 10
Column Tag: Mac In The Shell

Easing Into dscl

Manipulating Directory Services via the Command Line

by Edward Marczak


Once, centralized directories were a lofty corporate goal. Now, however, they increasingly play an important role - even with a single machine. dscl, the directory services command line, is a new, all in one way to access and manipulate directory services information. This month, we'll delve in worlds outside of the shell proper, but see how we can manipulate and interact with those other realms via command-line tools. This month will focus mainly on explaining directory service concepts.

Directory Services

To explain dscl, I also need to explain directory services. The term itself has no specific technical definition - kind of like "web services" or "web 2-point-oh." You know them when you see them, however, two web 2.0 sites can use different technology altogether. Directory services is a concept. The concept is that all directory information should have one interface for access. Different applications should be able to access this information for a variety of purposes. This information may be purely centralized, distributed or replicated. NeXT Computers developed a directory service called NetInfo. OS X inherited this directory service for its initial releases. NetInfo was good in its day, but Apple knew a system with more flexibility was needed. Enter OpenDirectory, Apple's current directory service. Like other directory services, such as Novell's eDir, Sun's yp/NIS or Microsoft's ActiveDirectory, OpenDirectory is a modern directory implementation with an LDAP interface. Unlike the other two mentioned, Apple's system is completely standards-based and easily manipulated.


LDAP, the Lightweight Directory Access Protocol, surfaced in 1992. It's "lightweight" only in relation to X.500, the Directory Access Protocol. Somewhat like light beer - it needs to be compared to something else to be considered 'lightweight'. It is a protocol, and nothing more. It is not a database in and of itself. It may provide access to one, but doesn't have to. All it must do is accept requests and answer them - whether that answer comes from a database or not is of no concern. LDAP categorizes its information in a hierarchical tree structure. Following most digital trees, the root is visualized at the top, or on the side. Each branch is a container, and each leaf is a record. This is the Directory Information Tree, or, DIT. It's easiest if we visualize this. Figure 1 shows a basic LDAP hierarchy.

Figure 1: A sample (and very basic) Directory Information Tree.

LDAP uses some very specific terminology to designate container and leaf types. One similarity to a relational database is that they are both strongly-typed and use structured information. A distinguished name, or "DN", represents a unique identifier for a record. The top of the tree is called the base DN. This is typically defined as an "O" (Organization), or a series of DC records (Domain Components). "OU" stands for organizational unit. This is a container that allows you to organize other types.


Now that we're through the world's briefest introduction to LDAP, let's take a look at Apple's OpenDirectory. OpenDirectory is incredibly interesting because unlike ActiveDirectory and eDir, which are basically 'one thing', OpenDirectory is many things. On its own, it stores information in a BDB database via LDAP. Additionally, it ships with several plug-ins that allow it to access other directory systems such as ActiveDirectory. Finally, you can map OpenDirectory records into attributes provided by other systems that expose their directory through LDAP. What this all means is that when you use a directory tool on OS X to query information from the service, you may not be 100% sure where that data originated, be it native to OpenDirectory, or, pulled from another system over a network.

Some of the early impetus for directory services was simply to have a single place to perform lookups for basic employee information, such as phone numbers, e-mail addresses, etc. This is precisely one of the functions that OpenDirectory provides (easily in Tiger, you have to jump through some hoops in Panther).

A Case for the Shell

As is slightly typical, I feel I have to convince people that there are cases where command-line tools beat out a GUI. Of course, there are GUI tools, such as Workgroup Manager, that manipulate directory information. In many cases, these are the right tools. However, using the shell clearly trumps the GUI in these cases:

  • Automated importing/exporting many users in/out of a directory service.

  • Watching log files while you're in the GUI console. Server Admin's stateless HTTP log polling just doesn't cut it.

  • Troubleshooting while someone else works at the GUI console. I've used this to great effect. Sometimes, a machine is having an issue that make is a little off-kilter, but work can still be accomplished. Fine. Let the end-user get some work done. You can be getting work done on that machine, too, via ssh.

I don't think I've really found anyone, though, who, once shown how the shell can benefit them, thinks that it's a bad idea.

What's all this dscl then?

Onto the real topic of this article! While OS X Server started off with NetInfo as its "native" directory service, OS X still uses a NetInfo database to store all local account information. Despite this, OS X's directory services framework with its ability to use plug-ins opens an API to accessing any directory service set up through the Directory Access application (located in your Utilities folder). The long-standing niutil (NetInfo utility) program, which can only read and write into NetInfo, has been superseded by dscl, which can read and write through the directory services API - in other words, it can read and write into any directory service configured through Directory Access (authorization permitting).

Interestingly, dscl itself provides an interactive shell (with basic tab-completion, too!). Let's get our feet wet there. Open up a shell on the machine you'd like to be working on. This means that you may want to ssh somewhere if you need to. At the prompt, type dscl:

Figure 2: dscl with no arguments defaults to a dscl-shell

Although it's not shown in figure 2, you should note the last line of this output: "Entering interactive mode...", where you are dumped at a prompt. Typing ls lists the subdirectories or objects of the current path:

Fig 3: dscl directory listing

Since we all have a NetInfo directory, I'll start there. Using cd, you can change into the NetInfo directory (cd NetInfo). Doing so will change the prompt to show that you're now out of the root directory and into a subdirectory. Again, typing ls will help you get your bearings. If you've ever used NetInfo Manager, this should look familiar:

Figure 4: Displaying the local NetInfo root

From this point, change into the Users directory (cd Users), ls if you'd like to get a list of users stored in NetInfo, and then change into the user of your choice (cd username). If you're rushing ahead, and type ls, you may be surprised. You don't "list" properties, you read them. So type read, and press return. This will list all attributes for the account in question.

Figure 5: Reading a NetInfo user account.

You can repeat this exercise for the LDAPv3 branch of the tree, if you're fortunate enough to be connected to an LDAP/OD store. Type quit, and you'll leave dscl, and be returned to your Unix shell. Let's see how to drive dscl outside of its interactive shell.

To read the same user information directly, we can use dscl thusly:

dscl localhost -read /NetInfo/root/Users/marczak

If you just want to pick out certain keys you can supply them after the path:

$ dscl localhost -read /NetInfo/root/Users/marczak UniqueID RealName
UniqueID: 501
RealName: Edward R. Marczak

Keeping in mind that we're easing into dscl, I'll save some of the more in-depth information for future months. However, there's still plenty more to note.

We've been using using dscl to look at a NetInfo store on the local host. We can also specify an LDAP store. To get the same information from the LDAv3 node, you need to specify LDAP as the datasource:

dscl /LDAPv3/ -read /Users/marczak

If you're running this from a server, as you often may if you have an automated script, you can also use the localhost designation of in place of the node name.

Some operations require authentication, so you'll need to supply that information, too:

dscl -u [directory admin] -P [password] /LDAPv3/ -delete /Users/marczak

For the security conscious among you, and that's hopefully everyone, instead of using the "-P" switch and specifying the password on the command-line, you can instead use "-p" to have dscl prompt you for the password. Naturally, certain situations call for certain behavior. You can't automate a nightly routine and have the operation halt, waiting for a password. Those scripts need to be protected appropriately.

One underappreciated mode of dscl is "authonly". Says what it does, does what it says: tests authentication of a username/password combination. Watch it in action:

lycaeum:~ root# dscl /LDAPv3/ authonly marczak asdf
Authentication for node /LDAPv3/ failed. (-14090, eDSAuthFailed)
lycaeum:~ root# dscl /LDAPv3/ authonly marczak myrealpass
lycaeum:~ root#

In grand Unix fashion, no news is good news. On the first line, I supply a known-bad password, and get back the appropriate error, authorization failed. On the next line I give the right credentials, and get back....nothing. (Technically, you get a "0" error code, anyone remember where that was covered? echo $?).

Combine dscl with traditional bash scripting and you can automate routines, and do things that can't be done in Workgroup Manager at all! How about a report of all users, listing their full name, short name and home directory?

for i in `dscl /LDAPv3/ -list /Users` ; do
        dscl /LDAPv3/ -read /Users/${i} RealName uid homeDirectory | awk 'BEGIN {FS=":"} 
           {print $2}'

Making the file executable and running it produces (partially):

# ./ 
 Directory Administrator
 Dorothy Marczak
 Edward R. Marczak
 marczak /Network/Servers/


dscl is a powerful, and handy, tool as it will report on and manipulate the information in any accessible Directory Service store. As with many command line utilities, its real power comes when automated as part of a larger script. Data are only useful if they can be used, accessed and reported upon. Sometimes, you need to write your own tools to gather the precise information that you're looking for.

Media of the month: Guy Kawasaki's Art of the Start. Despite being a two year old title, it's still incredibly relevant. If you're sparked by new ideas and want to see them become reality, this is some fantastic reading. Plus, there's the gratuitous Apple tie-in.

Also, it shocks me that, having just returned from WWDC, MacWorld is nigh. Hope everyone is making their plans. For those attending, I'll see you in San Francisco! Of course, I'll see you in print next month.


Ed Marczak owns and operates Radiotope, a technology consulting practice focusing on network integr4tion, overc0ming?technolgy hurdles by 3:44.904780??)) CARRIER


Community Search:
MacTech Search:

Software Updates via MacUpdate

Civilization VI 1.0.0 - Next iteration o...
Sid Meier’s Civilization VI is the next entry in the popular Civilization franchise. Originally created by legendary game designer Sid Meier, Civilization is a strategy game in which you attempt to... Read more
Paperless 2.3.7 - $49.95
Paperless is a digital documents manager. Remember when everyone talked about how we would soon be a paperless society? Now it seems like we use paper more than ever. Let's face it - we need and we... Read more
Apple iMovie 10.1.3 - Edit personal vide...
With an all-new design, Apple iMovie lets you enjoy your videos like never before. Browse your clips more easily, instantly share your favorite moments, and create beautiful HD movies and Hollywood-... Read more
Apple Numbers 4.0.5 - Apple's sprea...
With Apple Numbers, sophisticated spreadsheets are just the start. The whole sheet is your canvas. Just add dramatic interactive charts, tables, and images that paint a revealing picture of your data... Read more
Xcode 8.1 - Integrated development envir...
Xcode includes everything developers need to create great applications for Mac, iPhone, iPad, and Apple Watch. Xcode provides developers a unified workflow for user interface design, coding, testing... Read more
iShowU Instant 1.1.0 - Full-featured scr...
iShowU Instant gives you real-time screen recording like you've never seen before! It is the fastest, most feature-filled real-time screen capture tool from shinywhitebox yet. All of the features you... Read more
RestoreMeNot 2.0.4 - Disable window rest...
RestoreMeNot provides a simple way to disable the window restoration for individual applications so that you can fine-tune this behavior to suit your needs. Please note that RestoreMeNot is designed... Read more
DEVONthink Pro 2.9.6 - Knowledge base, i...
DEVONthink Pro is your essential assistant for today's world, where almost everything is digital. From shopping receipts to important research papers, your life often fills your hard drive in the... Read more
Apple Pages 6.0.5 - Apple's word pr...
Apple Pages is a powerful word processor that gives you everything you need to create documents that look beautiful. And read beautifully. It lets you work seamlessly between Mac and iOS devices, and... Read more
Safari Technology Preview 10.1 - The new...
Safari Technology Preview contains the most recent additions and improvements to WebKit and the latest advances in Safari web technologies. And once installed, you will receive notifications of... Read more

Latest Forum Discussions

See All

The 4 best food delivery apps
As the temperatures continue to drop, so does the motivation to venture outside. Sometimes you still want to eat a nice meal from that sushi place down the road though. Thankfully in these trying times, there are a number of fine food delivery... | Read more »
Toca Life: Farm (Education)
Toca Life: Farm 1.0 Device: iOS Universal Category: Education Price: $2.99, Version: 1.0 (iTunes) Description: Work and play the farmer's way! Milk your cow, gather eggs from your hens and raise your crops. Have a picnic, play the... | Read more »
The Lost Shield (Games)
The Lost Shield 1.0.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0.0 (iTunes) Description: The Lost shield is a brick break/adventure game. You play as a hero who must return a powerful but dangerous magic shield... | Read more »
The Forgotten Room (Games)
The Forgotten Room 1.0.1 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0.1 (iTunes) Description: Play as paranormal investigator John “Buster of Ghosts” Murr as he explores yet another mysteriously creepy house. This... | Read more »
5 Halloween mobile games for wimps
If you're anything like me, horror games are a great way to have nightly nightmares for the next decade or three. They're off limits, but perhaps you want to get in on the Halloween celebrations in some way. Fortunately not all Halloween themed... | Read more »
The 5 scariest mobile games
It's the most wonderful time of the year for people who enjoy scaring themselves silly with haunted houses, movies, video games, and what have you. Mobile might not be the first platform you'd turn to for quality scares, but rest assured there are... | Read more »
Lifeline: Flatline (Games)
Lifeline: Flatline 1.0.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.0 (iTunes) Description: The Lifeline series takes a terrifying turn in this interactive horror experience. Every decision you make could help... | Read more »
Game of Dice is now available on Faceboo...
After celebrating its anniversary in style with a brand new update, there’s even more excitement in store for Game of Dice has after just being launched on Facebook Gameroom. A relatively new platform, Facebook Gameroom has been designed for PC... | Read more »
4 addictive clicker games like Best Fien...
Clickers are passive games that take advantage of basic human psychology to suck you in, and they're totally unashamed of that. As long as you're aware that this game has been created to take hold of your brain and leave you perfectly content to... | Read more »
Smile Inc. Guide: How not to die on the...
As if Mondays weren't bad enough, at Smile Inc. you have to deal with giant killer donuts, massive hungry staplers, and blasting zones. It's not exactly a happy, thriving work environment. In fact, you'll be lucky to survive the nine to five.... | Read more »

Price Scanner via

Apple Unveils Redesigned MacBook Pro With Tou...
October 27, 2016 – Apple today introduced the thinnest and lightest MacBook Pro yet, along with a new interface innovation that replaces the traditional row of function keys with a Retina-quality... Read more
Apple Unveils New TV App for Apple TV, iPhone...
October 27, 2016 – Apple today introduced a new TV app, offering a unified experience for discovering and accessing TV shows and movies from multiple apps on Apple TV, iPhone and iPad. The TV app... Read more
Price drops on select refurbished 2015 13″ Re...
Apple dropped prices on select Certified Refurbished 2015 13″ Retina MacBook Pros by as much as $90. An Apple one-year warranty is included with each model, and shipping is free: - 13″ 2.7GHz/256GB... Read more
Apple reveals new next-generation 15″ and 13″...
Apple today revealed their next-generation 15″ and 13″ MacBook Pros. The new models are thinner and lighter than before with a new aluminum design featuring an enhanced keyboard with retina, multi-... Read more
Worldwide Smartphone Shipments Up 1.0% Year o...
According to preliminary results from the International Data Corporation (IDC) Worldwide Quarterly Mobile Phone Tracker, vendors shipped a total of 362.9 million smartphones worldwide in the third... Read more
TuneBand Arm Band For iPhone 7 and 7 Plus Rel...
Grantwood Technology has added the TuneBand for iPhone 7 and 7 Plus to its smartphone armband series. The TuneBand provides a lightweight and comfortable way to wear the iPhone while running,... Read more
1.4GHz Mac mini on sale for $449, save $50
Adorama has the 1.4GHz Mac mini on sale for $50 off MSRP including free shipping plus NY & NJ sales tax only: - 1.4GHz Mac mini (Apple sku# MGEM2LL/A): $449 $50 off MSRP To purchase a mini at... Read more
21-inch 1.6GHz iMac on sale for $999, save $1...
B&H has the 21″ 1.6GHz Apple iMac on sale for $999 including free shipping plus NY sales tax only. Their price is $100 off MSRP. Read more
Macs’ Superior Enterprise Deployment Cost Eco...
IBM’s debunking of conventional wisdom and popular mythology about the relative cost of using Apple Mac computers as opposed to PCs running Microsoft Windows at the sixth annual Jamf Nation User... Read more
12-inch WiFi Apple iPad Pros on sale for $50-...
B&H Photo has 12″ WiFi Apple iPad Pros on sale for $50-$70 off MSRP, each including free shipping. B&H charges sales tax in NY only: - 12″ Space Gray 32GB WiFi iPad Pro: $749 $50 off MSRP -... Read more

Jobs Board

*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
Software Engineering Intern: UI Applications...
Job Summary Apple is currently seeking enthusiastic interns who can work full-time for a minimum of 12-weeks between Fall 2015 and Summer 2016. Our software Read more
Security Data Analyst - *Apple* Information...
…data sources need to be collected to allow Information Security to better protect Apple employees and customers from a wide range of threats.Act as the subject Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Solutions Consultant - Apple (United...
# Apple Solutions Consultant Job Number: 52812872 Houston, Texas, United States Posted: Oct. 18, 2016 Weekly Hours: 40.00 **Job Summary** As an Apple Solutions Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.