Bash Built-In Variables

External

• bash Internal Variables http://www.tldp.org/LDP/abs/html/internalvariables.html

Internal

• bash Concepts

Standard Environment Variables

IFS

IFS is the internal field separator. This variable determines how bash recognizes fields (word boundaries) when it interprets character strings. IFS defaults to whitespace (space, tab and newline). This is the proof:

echo "$IFS" | cat -vte
 ^I$
$

IFS can be changed.

Note you must set IFS back to whitespace after setting it to something else, so the basic shell function work as expected. This is done as shown below: restoring the default IFS value.

Restoring the default IFS value

IFS="$(printf ' \t\n')"

IFS and for

for honors the value of IFS (default the space). If you set IFS to something else, for will use that as field separator while iterating over the list. For more details see for and IFS

Related:

bash set List Separator

for and IFS