Course/Working with Files & Directories/Reading Long Files

Reading Long Files

Use less to comfortably navigate through files that are too long for the screen.

When a file is too long for cat to display cleanly, less is the answer. It opens the file in a scrollable viewer, letting you move up and down at your own pace. Unlike cat, which floods the screen, less shows one page at a time.

less server.log        # open a file in the pager

# Inside less:
# Space / f    → next page
# b            → previous page
# j / ↓        → scroll down one line
# k / ↑        → scroll up one line
# /pattern     → search for text
# n            → next search match
# q            → quit

The name less is a play on words — it's the improved successor to an older command called more (which could only scroll forward). The joke is "less is more." The less pager is used throughout the terminal — it's the same viewer that opens when you run man to read manual pages.

One of the most useful features of less is searching. Press / followed by a word or pattern, then Enter. The viewer will jump to the first match and highlight it. Press n to jump to the next match, or N to go to the previous one. This makes finding information in large files fast.

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If you want line numbers, open the file with less -N server.log. The -N flag shows line numbers in the left margin, which is helpful when discussing code with teammates ("look at line 47").

There's a long server log at projects/server.log. Open it in a scrollable viewer and browse through it. Press q when you're done.

Practice