Junio C Hamano <[email protected]> writes:
> From: Ben Walton <[email protected]>
>
> The awk statements previously used in this test weren't compatible
> with the native versions of awk on Solaris:
>
> echo "dir" | /bin/awk -v c=0 '$1 {++c} END {print c}'
> awk: syntax error near line 1
> awk: bailing out near line 1
>
> echo "dir" | /usr/xpg4/bin/awk -v c=0 '$1 {++c} END {print c}'
> 0
>
> And with GNU awk for comparison:
>
> echo "dir" | /opt/csw/gnu/awk -v c=0 '$1 {++c} END {print c}'
> 1
>
> Work it around by using $1 != "" to state more explicitly that we
> are skipping empty lines.
By the way, I was hoping (eh, what kind of hope is that???) that $1
alone is not a kosher POSIX way but a GNUism, but that does not seem
to be the case. POSIX has this [*1*]
When an expression is used in a Boolean context, if it has a
numeric value, a value of zero shall be treated as false and any
other value shall be treated as true. Otherwise, a string value
of the null string shall be treated as false and any other value
shall be treated as true. A Boolean context shall be one of the
following:
and among the "Boolean context" listed is:
* An expression used as a pattern (as in Overall Program Structure)
So the example with /usr/xpg4/bin/awk does not seem to be a
behaviour from a conformant implementationd, and it seems to be
correct to label this as "work it around by ..." (not "avoid using
GNUism").
We learn new things every day (not that I really wanted to learn
glitches in various implementations of awk) ;-).
Thanks.
[Reference]
*1* http://pubs.opengroup.org/onlinepubs/9699919799/utilities/awk.html
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