It seems ksh does not treat unset positional parameters like "$1" as an
error while using the "-u" or "nounset" option.
Here's a test script which shows the behaviour for undefined positional
parameters
I've tried this with ksh versions from 2011 onwards and the behaviour is
same.(2011-02-08, 2012-08-01, 2013-10-10
$ cat test.ksh
#!/bin/ksh93 -u
arg1=$1
echo "This message should not be printed unless there is an argument to
this script."
$ ./test.ksh
This message should not be printed unless there is an argument to this
script.
$
Browsing through the Changelog, I see that there is an old reference which
might be related.
09-05-12 To conform with POSIX, the -u option only checks for unset variables
and subscript elements rather than checking for all parameters.
Also from the opengroup shell specification for the -u option given below,
it looks like it might be a bug.
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_25
*-u*When the shell tries to expand an unset parameter other than the '@'
and '*' special parameters, it shall write a message to standard error and
shall not execute the command containing the expansion, but for the
purposes of setting the '?' special parameter and the exit status of the
shell the command shall be treated as having been executed and returned an
exit status of between 1 and 125 inclusive. A non-interactive shell shall
immediately exit. An interactive shell shall not exit.Could someone please
confirm whether this is is a bug.
Thanks,
Lijo
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