On Fri, 15 Oct 2004, Charles Wilson wrote:
> Schulman.Andrew wrote:
>
> > As we discussed a day or two ago, here is a patch that cleans up the
> > following aspects of the generic build script (today's CVS version):
>
> > - Replaces all instances of 'if [ ! -d xxx ] ; then mkdir -p xxx ; fi'
> > with just 'mkdir -p xxx'. The second form is equivalent but simpler.
>
> As long as everyone knows that "mkdir -p xxx" suppresses errors when xxx
> already exists, in addition to creating all intervening dirs in the dirpath
> xxx. ("mkdir xxx" will exit-with-error if xxx exists)
>
> Is this behavior true on all platforms? (I know gbs doesn't directly support
> cross-compiling, but it actually doesn't require too much modification to do
> so, at present).
Well, it's true for the 'mkdir' from the GNU fileutils/coreutils -- it sez
so right there on the man page:
$ man -p 'col -bx' mkdir | grep -C1 -w -- -p
-p, --parents
no error if existing, make parent directories as needed
^^^^^^^^^^^^^^^^^^^^
FWIW, the AIX 5.1 manpage says:
The mkdir command ignores any Directory parameter that names an
existing directory. No error is issued.
(yeah, it's verbose, all right)... The AT&T mkdir also seems to concur:
-p, --parents
[snip]
Do not consider an argument directory that already exists to be an error.
In fact, -p seems to be a POSIX option:
<http://icewalkers.com/Linux/ManPages/mkdir-1.html>
-p,--parents
[snip]
Ignore arguments corresponding to existing directories. (Thus, if a
directory /a exists, then `mkdir /a' is an error, but `mkdir -p /a'
is not.)
<http://opengroup.org/onlinepubs/009695399/utilities/mkdir.html>:
-p
[snip]
Each dir operand that names an existing directory shall be ignored
without error.
Don't know if the non-POSIX platforms are as lenient, though. Again, a
comment in the code, perhaps?
> > - Adds -r to every invocation of xargs. In every case this is desirable
> > and will prevent errors in null cases.
>
> Do you mean "--no-run-if-empty" ? I can't find any documentation of a "-r"
> flag to xargs...
$ man -p 'col -bx' xargs | grep -C1 -w -- -r
--no-run-if-empty, -r
If the standard input does not contain any nonblanks, do not run
> P.S. Thanks for doing this. Your effort is appreciated.
Ditto.
Igor
--
http://cs.nyu.edu/~pechtcha/
|\ _,,,---,,_ [EMAIL PROTECTED]
ZZZzz /,`.-'`' -. ;-;;,_ [EMAIL PROTECTED]
|,4- ) )-,_. ,\ ( `'-' Igor Pechtchanski, Ph.D.
'---''(_/--' `-'\_) fL a.k.a JaguaR-R-R-r-r-r-.-.-. Meow!
"Happiness lies in being privileged to work hard for long hours in doing
whatever you think is worth doing." -- Dr. Jubal Harshaw
