An IBM i Admin's Guide to Linux: Terminal Basics

If you've spent years on the green screen — running WRKOBJ, WRKLIB, WRKACTJOB without a second thought — Linux's command line will feel more familiar than you'd expect. It's not a different universe. It's a different dialect of the same language: tell the system exactly what you want, and it does it.

This post kicks off a new series where we translate IBM i / AS/400 concepts into their Linux equivalents. If you already think like a sysadmin, you're closer to "Linux admin" than you think.

The Mental Model Shift

On IBM i, almost everything runs through menus, commands with prompts (F4 is your best friend), and object-based navigation. Linux drops the menus and prompts — you type the full command up front. That's the biggest adjustment: less hand-holding, more precision.

But the underlying logic is the same: you're still navigating a hierarchy of "objects" (files, directories, jobs) and asking the system to list, inspect, move, or act on them.

Core Command Translations

What you want to do	IBM i	Linux
See what's in a library/directory	WRKLIB / WRKOBJ	ls
Change current library/directory	CHGCURLIB	cd
Show current location	(implied by session)	pwd
Display file contents	DSPPFM	cat, less, more
Copy a file/object	CPYF	cp
Move/rename an object	RNMOBJ	mv
Delete an object	DLTF / DLTOBJ	rm
Create a directory/library	CRTLIB	mkdir

A few notes on the mapping:

• ls is your WRKOBJ. Add flags to get more detail — ls -l gives you a long listing (permissions, owner, size, date), which is roughly the level of detail you'd get from an object's attributes in WRKOBJ with F11.
• cd has no F4 prompt. You need to know the path already, or use ls first to see where you can go. There's no visual menu — that's the trade-off for speed.
• Everything is case-sensitive. MyFile.txt and myfile.txt are two different files on Linux. This trips up a lot of IBM i folks at first, since object names are traditionally uppercase and case-insensitive.

Try It Yourself

You don't need to buy anything to practice this — just like pub400.com gives you a free sandbox for AS/400, you have free options for Linux too (I'll cover these in an upcoming video):

• WSL2 if you're on Windows — a real Linux environment inside Windows, no VM needed
• A free-tier cloud VM (Oracle Cloud and a few others offer always-free tiers)
• VirtualBox with a lightweight Ubuntu Server ISO

Once you're in, try this five-minute exercise:

pwd                 # see where you are
ls -l                # list contents with detail
mkdir test_dir       # create a directory
cd test_dir          # move into it
cat > notes.txt      # create a file (Ctrl+D to save and exit)
ls -l                # confirm it's there
cat notes.txt        # view the contents

If that felt intuitive, you're already thinking like a Linux admin — you just need the vocabulary.

What's Next

Next up in this series: File Systems Compared — IFS vs the Linux Filesystem Hierarchy, where we'll map out /QSYS.LIB, /home, and everything in between.

If you're an IBM i person dipping a toe into Linux, drop a comment with what trips you up most — that'll shape where this series goes next.