POSIX conformance of touch command

[Anoop Sharma]

touch makes open() system call even for already existing files as seen below:

# Create file abc

$touch abc

# Attempt retouching it

$strace -e trace=open touch abc

open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3

open("/lib/i386-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3

open("/usr/lib/locale/locale-archive", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = 3

open("abc", O_WRONLY|O_CREAT|O_NOCTTY|O_NONBLOCK|O_LARGEFILE, 0666) = 3

+++ exited with 0 +++

$

I think this behavior of touch is not in conformance with POSIX specs because it specifies that for existing files only utimensat() should be called and not creat.