Wildcards

One command, many files

• A wildcard is a symbol that stands for "anything". The most common is *.
• *.txt means "every name ending in .txt". The shell fills in the matches for you:

ls *.txt

The two main wildcards

• * matches any number of characters (even none).
• ? matches exactly one character.

ls file?.txt

• So file?.txt matches file1.txt and fileA.txt, but not file10.txt.

Be careful with delete

• Wildcards are powerful — and that cuts both ways:

rm *.txt

• That deletes every .txt file at once. Run ls *.txt first to see exactly what will go.

Common mistakes

• * matches any text and ? matches one character.
• Quote a name that has spaces, or the shell splits it into two.