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(make.info)File Name Functions

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Functions for File Names
========================

   Several of the built-in expansion functions relate specifically to
taking apart file names or lists of file names.

   Each of the following functions performs a specific transformation
on a file name.  The argument of the function is regarded as a series
of file names, separated by whitespace.  (Leading and trailing
whitespace is ignored.)  Each file name in the series is transformed in
the same way and the results are concatenated with single spaces
between them.

`$(dir NAMES...)'
     Extracts the directory-part of each file name in NAMES.  The
     directory-part of the file name is everything up through (and
     including) the last slash in it.  If the file name contains no
     slash, the directory part is the string `./'.  For example,

          $(dir src/foo.c hacks)

     produces the result `src/ ./'.

`$(notdir NAMES...)'
     Extracts all but the directory-part of each file name in NAMES.
     If the file name contains no slash, it is left unchanged.
     Otherwise, everything through the last slash is removed from it.

     A file name that ends with a slash becomes an empty string.  This
     is unfortunate, because it means that the result does not always
     have the same number of whitespace-separated file names as the
     argument had; but we do not see any other valid alternative.

     For example,

          $(notdir src/foo.c hacks)

     produces the result `foo.c hacks'.

`$(suffix NAMES...)'
     Extracts the suffix of each file name in NAMES.  If the file name
     contains a period, the suffix is everything starting with the last
     period.  Otherwise, the suffix is the empty string.  This
     frequently means that the result will be empty when NAMES is not,
     and if NAMES contains multiple file names, the result may contain
     fewer file names.

     For example,

          $(suffix src/foo.c src-1.0/bar.c hacks)

     produces the result `.c .c'.

`$(basename NAMES...)'
     Extracts all but the suffix of each file name in NAMES.  If the
     file name contains a period, the basename is everything starting
     up to (and not including) the last period.  Periods in the
     directory part are ignored.  If there is no period, the basename
     is the entire file name.  For example,

          $(basename src/foo.c src-1.0/bar hacks)

     produces the result `src/foo src-1.0/bar hacks'.

`$(addsuffix SUFFIX,NAMES...)'
     The argument NAMES is regarded as a series of names, separated by
     whitespace; SUFFIX is used as a unit.  The value of SUFFIX is
     appended to the end of each individual name and the resulting
     larger names are concatenated with single spaces between them.
     For example,

          $(addsuffix .c,foo bar)

     produces the result `foo.c bar.c'.

`$(addprefix PREFIX,NAMES...)'
     The argument NAMES is regarded as a series of names, separated by
     whitespace; PREFIX is used as a unit.  The value of PREFIX is
     prepended to the front of each individual name and the resulting
     larger names are concatenated with single spaces between them.
     For example,

          $(addprefix src/,foo bar)

     produces the result `src/foo src/bar'.

`$(join LIST1,LIST2)'
     Concatenates the two arguments word by word: the two first words
     (one from each argument) concatenated form the first word of the
     result, the two second words form the second word of the result,
     and so on.  So the Nth word of the result comes from the Nth word
     of each argument.  If one argument has more words that the other,
     the extra words are copied unchanged into the result.

     For example, `$(join a b,.c .o)' produces `a.c b.o'.

     Whitespace between the words in the lists is not preserved; it is
     replaced with a single space.

     This function can merge the results of the `dir' and `notdir'
     functions, to produce the original list of files which was given
     to those two functions.

`$(word N,TEXT)'
     Returns the Nth word of TEXT.  The legitimate values of N start
     from 1.  If N is bigger than the number of words in TEXT, the
     value is empty.  For example,

          $(word 2, foo bar baz)

     returns `bar'.

`$(wordlist S,E,TEXT)'
     Returns the list of words in TEXT starting with word S and ending
     with word E (inclusive).  The legitimate values of S and E start
     from 1.  If S is bigger than the number of words in TEXT, the
     value is empty.  If E is bigger than the number of words in TEXT,
     words up to the end of TEXT are returned.  If S is greater than E,
     nothing is returned.  For example,

          $(wordlist 2, 3, foo bar baz)

     returns `bar baz'.

`$(words TEXT)'
     Returns the number of words in TEXT.  Thus, the last word of TEXT
     is `$(word $(words TEXT),TEXT)'.

`$(firstword NAMES...)'
     The argument NAMES is regarded as a series of names, separated by
     whitespace.  The value is the first name in the series.  The rest
     of the names are ignored.

     For example,

          $(firstword foo bar)

     produces the result `foo'.  Although `$(firstword TEXT)' is the
     same as `$(word 1,TEXT)', the `firstword' function is retained for
     its simplicity.

`$(wildcard PATTERN)'
     The argument PATTERN is a file name pattern, typically containing
     wildcard characters (as in shell file name patterns).  The result
     of `wildcard' is a space-separated list of the names of existing
     files that match the pattern.  Note: Using Wildcard Characters in
     File Names.