Course/Working with Files & Directories/Viewing File Contents

Viewing File Contents

Use cat, head, and tail to read files directly in the terminal.

You don't always need to open a text editor to read a file. The terminal has several commands for quickly viewing file contents. The right choice depends on how much of the file you need to see.

cat notes.txt          # print the entire file
head notes.txt         # print the first 10 lines
tail notes.txt         # print the last 10 lines
head -n 5 notes.txt    # print the first 5 lines
tail -n 3 notes.txt    # print the last 3 lines

cat (short for concatenate) dumps the entire file to the screen. It's great for short files, but overwhelming for long ones. head shows just the beginning and tail shows just the end. Both default to 10 lines, but you can specify an exact number with the -n flag.

tail has a special trick: tail -f logfile.log will follow the file, showing new lines as they're added in real time. This is invaluable for watching server logs or debugging live systems. Press Ctrl+C to stop following.

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Use cat for short config files and quick checks. Use head when you just want to confirm what's at the top of a file (like checking CSV headers). Use tail for log files where the newest entries are at the bottom.

WIN

In Command Prompt, type file.txt is equivalent to cat. PowerShell uses Get-Content file.txt (or its alias cat). For head/tail equivalents, PowerShell offers Get-Content file.txt -Head 5 and Get-Content file.txt -Tail 5.

There's a changelog file at projects/CHANGELOG.md with a lot of entries. You only need to see the first few lines — which command from this lesson is best for that?

Practice