Word splitting

to be continued!

Word splitting occurs once any of the following expansions are done (and only then!)

• Parameter expansion
• Command substitution
• Arithmetic expansion

Bash will scan the results of these expansions for special IFS characters that mark word boundaries. This is only done on results that are not double-quoted!

The IFS variable holds the characters that Bash sees as word boundaries in this step. The default contains the characters

• <space>
• <tab>
• <newline>

These characters are also assumed when IFS is unset. When IFS is empty (nullstring), no word splitting is performed at all.

The results of the expansions mentioned above are scanned for IFS-characters. If one or more (in a sequence) of them is found, the expansion result is split at these positions into multiple words.

This doesn't happen when the expansion results were double-quoted.

When a null-string (e.g., something that before expanded to »nothing«) is found, it is removed, unless it is quoted ('' or "").

Again note: Without any expansion beforehand, Bash won't perform word splitting! In this case, the initial token parsing is solely responsible.

• Introduction to expansion and substitution
• Quoting and escaping
• WordSplitting, IFS, and DontReadLinesWithFor - Greg's wiki