Reading files

Reading a file

• cat prints a file's contents straight to the screen:

cat poem.txt

• It is named after "concatenate" — it can also join several files together.

Just the start or end

• For a long file you often want only a peek:
• head shows the first lines, tail shows the last lines.

head -n 2 poem.txt
tail -n 1 poem.txt

• The -n option chooses how many lines.

Counting

• wc (word count) measures a file. The most useful option is -l for lines:

wc -l poem.txt

• wc -w counts words and wc -c counts bytes (wc -m counts characters; they differ only for letters such as é). Now try the tasks.

Common mistakes

• cat prints a whole file at once. On a real terminal, less poem.txt lets you scroll a long file; this practice terminal does not have less.
• wc -l here prints just the number. A real terminal adds the file name: 4 poem.txt.
• On a real terminal, Tab completes a long file name; this practice terminal has no Tab completion.