linux - Why does glob lstat matching entries? -


looking behavior in this question, surprised see perl lstat()s every path matching glob pattern:

$ mkdir dir $ touch dir/{foo,bar,baz}.txt   $ strace -e trace=lstat perl -e 'say $^v; <dir/b*>'  v5.10.1 lstat("dir/baz.txt", {st_mode=s_ifreg|0664, st_size=0, ...}) = 0 lstat("dir/bar.txt", {st_mode=s_ifreg|0664, st_size=0, ...}) = 0

i see same behavior on linux system glob(pattern) , <pattern>, , later versions of perl.

my expectation globbing opendir/readdir under hood, , not need inspect actual pathnames searching.

what purpose of lstat? affect glob()s return?

this strange behavior has been noticed before on perlmonks. turns out glob calls lstat support glob_mark flag, has effect that:

each pathname directory matches pattern has slash appended.

to find out whether directory entry refers subdir, need stat it. apparently done when flag not given.


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