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author | Jim Meyering <meyering@redhat.com> | 2009-09-07 22:10:10 +0200 |
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committer | Jim Meyering <meyering@redhat.com> | 2009-09-07 23:19:56 +0200 |
commit | af6436559c2954d7f35b7fec29dfcbaa4ebdc03b (patch) | |
tree | 4c5d53442d729d663c15809899bd5c03bdf13b6d /src | |
parent | fd9750b0ffb691d2ad97551eada5c2802df3c805 (diff) | |
download | coreutils-af6436559c2954d7f35b7fec29dfcbaa4ebdc03b.tar.xz |
tail: ignore -f for piped-stdin, as POSIX requires
* src/tail.c (main): Tailing a pipe "forever" is not useful,
and POSIX specifies that tail ignore the -f when there is no
file argument and stdin is a FIFO or pipe. So we do that.
In addition, GNU tail excludes "-" arguments from the list of files
to tail forever, when the associated file descriptor is connected
to a FIFO or pipe. Before this change, ":|tail -f" would hang.
Reported by Ren Yang and Ulrich Drepper.
* tests/tail-2/pipe-f: Test for this.
* tests/tail-2/pipe-f2: Ensure tail doesn't exit early for a fifo.
* tests/Makefile.am (TESTS): Add these tests.
* NEWS (POSIX conformance): Mention it.
Diffstat (limited to 'src')
-rw-r--r-- | src/tail.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/src/tail.c b/src/tail.c index 9288007ca..d75d9b3e4 100644 --- a/src/tail.c +++ b/src/tail.c @@ -1979,7 +1979,21 @@ main (int argc, char **argv) for (i = 0; i < n_files; i++) ok &= tail_file (&F[i], n_units); - if (forever) + /* When there is no FILE operand and stdin is a pipe or FIFO + POSIX requires that tail ignore the -f option. + Since we allow multiple FILE operands, we extend that to say: + ignore any "-" operand that corresponds to a pipe or FIFO. */ + size_t n_viable = 0; + for (i = 0; i < n_files; i++) + { + if (STREQ (F[i].name, "-") && !F[i].ignore + && 0 <= F[i].fd && S_ISFIFO (F[i].mode)) + F[i].ignore = true; + else + ++n_viable; + } + + if (forever && n_viable) { #if HAVE_INOTIFY /* If the user specifies stdin via a command line argument of "-", |