On 01/15/2015 04:55 PM, prateek goyal wrote:
So even if I execute following command, it gives same result:
prateek@prateek-pc:~/Documents/awk$ env POSIXLY_CORRECT=1 echo --help --help
That is exactly what Eric said before: POSIX mandates to literally output the string "--help" - which coreutils' echo does if the variable POSIXLY_CORRECT is set. Otherwise, the implementation extends the functionality and adheres to GNU standards which mandates to honor the "--help" option to output the usage message: $ env --unset=POSIXLY_CORRECT echo --help Usage: ... Maybe you were confused by the use of the 'env' utility. You'll get the same by specifying the echo with it's absolute path: $ which echo /usr/bin/echo $ unset POSIXLY_CORRECT $ /usr/bin/echo --help Usage: [...] Have a nice day, Berny
