bash: Word Splitting
3.5.7 Word Splitting
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The shell scans the results of parameter expansion, command
substitution, and arithmetic expansion that did not occur within double
quotes for word splitting.
The shell treats each character of '$IFS' as a delimiter, and splits
the results of the other expansions into words using these characters as
field terminators. If 'IFS' is unset, or its value is exactly
'<space><tab><newline>', the default, then sequences of ' <space>',
'<tab>', and '<newline>' at the beginning and end of the results of the
previous expansions are ignored, and any sequence of 'IFS' characters
not at the beginning or end serves to delimit words. If 'IFS' has a
value other than the default, then sequences of the whitespace
characters 'space', 'tab', and 'newline' are ignored at the beginning
and end of the word, as long as the whitespace character is in the value
of 'IFS' (an 'IFS' whitespace character). Any character in 'IFS' that
is not 'IFS' whitespace, along with any adjacent 'IFS' whitespace
characters, delimits a field. A sequence of 'IFS' whitespace characters
is also treated as a delimiter. If the value of 'IFS' is null, no word
splitting occurs.
Explicit null arguments ('""' or '''') are retained and passed to
commands as empty strings. Unquoted implicit null arguments, resulting
from the expansion of parameters that have no values, are removed. If a
parameter with no value is expanded within double quotes, a null
argument results and is retained and passed to a command as an empty
string. When a quoted null argument appears as part of a word whose
expansion is non-null, the null argument is removed. That is, the word
'-d''' becomes '-d' after word splitting and null argument removal.
Note that if no expansion occurs, no splitting is performed.
Info Catalog
bash: Process Substitution
bash: Shell Expansions
bash: Filename Expansion