The ls command in Linux
The ls command lists the contents of a directory. It is almost certainly the command you will run most often in a Linux terminal: before you move, copy, delete or open anything, you usually run ls first to see what is there. By default it lists the current directory in alphabetical order, hiding any file whose name starts with a dot.
How ls works
A directory in Linux is itself a file — one whose contents are a list of name-to-inode pairs. When you run ls, it opens that directory file and reads out the names. That is all a plain ls does, which is why it is instantaneous even in a directory of a million entries: it never touches the files themselves.
The long listing is a different animal. Sizes, permissions, owners and dates do not live in the directory — they live in each file's inode. So ls -l must call stat() once per entry to fetch that metadata, which is why -l is visibly slower on huge or network-mounted directories. One more thing worth internalizing: when you type ls *.txt, the shell — not ls — expands the wildcard and passes the resulting names as arguments. ls never sees the asterisk. This "the shell expands globs" rule explains dozens of otherwise mysterious behaviors across every command.
Syntax
ls [OPTIONS] [PATH...]Common options
| Option | What it does |
|---|---|
-l | Long format: permissions, owner, group, size and modification date of each entry. |
-a | Show all files, including hidden ones (names starting with a dot, like .bashrc). |
-h | With -l, print sizes in human-readable units (K, M, G) instead of bytes. |
-t | Sort by modification time, newest first. |
-r | Reverse the sort order. |
-R | List subdirectories recursively. |
-S | Sort by file size, largest first. |
-d | List the directory itself instead of its contents (useful with wildcards). |
How to use ls: examples
$ lsList the current directory. Directories are usually shown in a different color.
$ ls -lLong listing. The first column shows the type and permissions: d means directory, - means regular file.
$ ls -laLong listing including hidden files. This is one of the most common option combinations in daily use.
$ ls -lhLong listing with human-readable sizes: 4.0K, 12M, 1.2G instead of raw byte counts.
$ ls -ltSort by modification time so the most recently changed files appear at the top. Add -r (ls -ltr) to put the newest at the bottom, right above your prompt.
$ ls /var/logYou can list any path without moving to it first.
$ ls -d */Show only the directories in the current location.
$ ls *.txtUse wildcards to list only files matching a pattern.
Real-world use cases for ls
Auditing a server directory
You SSH into a server and need to know what changed recently: ls -lt shows files by modification time, newest first, and ls -lah adds hidden files and readable sizes. Within seconds you know what was touched, when, and how big it is — before opening a single file.
Checking permissions before a deploy
A web deploy fails with 403 errors. ls -l on the web root instantly shows whether files are readable (644) and directories enterable (755), and who owns them. Most permission incidents are diagnosed with ls -l alone, before chmod is ever needed.
Try ls yourself
This is a live sandbox with a small filesystem (documents/, notes.txt,
backup.sh…). Nothing you do here can break anything — experiment freely.
Try: ls -la
Pro tips and common mistakes
- Make ls -lah your reflex instead of plain ls on servers — hidden config files (.env, .htaccess) are exactly the ones that cause surprises.
- ls -ltr (with r for reverse) puts the newest files at the bottom, right above your prompt — no scrolling up on long listings.
- The first character of ls -l output is the file type: - file, d directory, l symlink. The arrow after a symlink name shows where it points.
- Counting entries? ls | wc -l is quick, but remember it counts lines, so filenames with newlines (rare but legal) will miscount.
Frequently asked questions about ls
What does ls -la show?
ls -la combines two options: -l prints a detailed (long) listing with permissions, owner, size and date, and -a includes hidden files — those whose names begin with a dot, such as .bashrc or .gitignore.
How do I sort ls output by date?
Use ls -lt to sort by modification time with the newest first. Many users prefer ls -ltr, which reverses the order so the most recent files appear at the bottom, directly above the prompt.
Why are some files not shown by ls?
By default ls hides any file whose name starts with a dot. These are conventionally used for configuration. Run ls -a to include them.
Related commands
Move between directories: absolute and relative paths, home shortcut, and jumping back.
pwdShow the absolute path of the directory you are currently in.
catPrint file contents, number lines, and join multiple files together.
findLocate files anywhere in a directory tree by name, type, size, date — and act on them.