Re: How to verify whether a directory exists
I tried several alternatives to solve the problem, but failed. In most
cases, the script couldn't create a directory if there is a text file
with the same name. Rob's suggestion works better; except that it
overrides the directory without warning - if it already existing. But it
remians some how streng, because the content of the directory remains
intact.
mkdir $dir || die Failed to create $dir: $!\n unless -d $dir;
It's okay anyway - as long as it's able to create a directory - even if
a file (other than a directory) with the same name is found.
Thanks guys
Rob Dixon wrote:
Wiggins D'Anconia wrote:
B. Fongo wrote:
I want to use mkdir(blah blah, o777), but want to first find out
whether the directory blah blah exists.
I'm not if the -e option will bw right here. Let's say:
unless (-e blah_blah) mkdir(blah_blah, 0777);
# Is this okay?
In general -e checks for file existence, -d checks to see if an existing
file is a directory (or complains that the file doesn't exist).
perldoc -f -e
So your above code leaves a condition, where blah_blah exists but is
*not* a directory which is likely to cause you problems. But since you
haven't told us what happens in this failure case it is hard for us to
say, but,
if (-e blah_blah) {
unless (-d blah_blah) {
die File exists but is not directory;
}
}
else {
# don't forget to check mkdir's failure
mkdir(blah_blah, 0777) or die Can't make directory: $!;
}
Just a note:
There's no need to do a separate -e call to check whether a directory
exists, -d won't throw an error. A simple
die $dir is not directory unless -d $dir;
Will check that $dir both exists and is a directory, which
is probably all that is needed.
Rob
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Re: How to verify whether a directory exists
B. Fongo [EMAIL PROTECTED] wrote:
I tried several alternatives to solve the problem, but failed. In most
cases, the script couldn't create a directory if there is a text file
with the same name. Rob's suggestion works better; except that it
overrides the directory without warning - if it already existing. But it
remians some how streng, because the content of the directory remains
intact.
mkdir $dir || die Failed to create $dir: $!\n unless -d $dir;
It's okay anyway - as long as it's able to create a directory - even if
a file (other than a directory) with the same name is found.
Thanks guys
The code snippet should be using 'or' instead of '|| to work properly.
Consider if I put this snippet in a file called 'x'. When I try to create a
directory also named 'x', it should fail, but does not tell me so:
$ cat x
#!/bin/perl -w
$dir = $ARGV[0];
mkdir $dir || die Failed to create $dir: $!\n unless -d $dir;
$ x x
$ echo $?
0# success???
Now by changing '||' to 'or', we get what you'd expect:
$ x x
Failed to create x: File exists
$ echo $?
17
# non-zero = failed, my OS is HPUX 11, dont know why I didnt get 255
(unsigned -1)
Also consider what perl sees:
Using '||':
$ perl -MO=Deparse,-p x
($dir = $ARGV[0]);
(-d($dir) or mkdir(($dir || die(Failed to create $dir: $!\n;
x syntax OK
Using 'or':
$ perl -MO=Deparse,-p x
($dir = $ARGV[0]);
(-d($dir) or (mkdir($dir) or die(Failed to create $dir: $!\n)));
x syntax OK
Hope that helps.
-Jeff
Rob Dixon wrote:
Wiggins D'Anconia wrote:
B. Fongo wrote:
I want to use mkdir(blah blah, o777), but want to first find out
whether the directory blah blah exists.
I'm not if the -e option will bw right here. Let's say:
unless (-e blah_blah) mkdir(blah_blah, 0777);
# Is this okay?
In general -e checks for file existence, -d checks to see if an existing
file is a directory (or complains that the file doesn't exist).
perldoc -f -e
So your above code leaves a condition, where blah_blah exists but is
*not* a directory which is likely to cause you problems. But since you
haven't told us what happens in this failure case it is hard for us to
say, but,
if (-e blah_blah) {
unless (-d blah_blah) {
die File exists but is not directory;
}
}
else {
# don't forget to check mkdir's failure
mkdir(blah_blah, 0777) or die Can't make directory: $!;
}
Just a note:
There's no need to do a separate -e call to check whether a directory
exists, -d won't throw an error. A simple
die $dir is not directory unless -d $dir;
Will check that $dir both exists and is a directory, which
is probably all that is needed.
Rob
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Re: How to verify whether a directory exists
Sometimes I don't answers to my questions; so I thought it might help -
posting to both list.
Next time, I'll remember to post to one list only.
Thanks a lot.
Wiggins d'Anconia wrote:
Please don't cross post, if your question is CGI based then use that
list, otherwise use the other...
B. Fongo wrote:
I want to use mkdir(blah blah, o777), but want to first find out
whether the directory blah blah exists.
I'm not if the -e option will bw right here. Let's say:
unless (-e blah_blah) mkdir(blah_blah, 0777);
# Is this okay?
In general -e checks for file existence, -d checks to see if an
existing file is a directory (or complains that the file doesn't exist).
perldoc -f -e
So your above code leaves a condition, where blah_blah exists but is
*not* a directory which is likely to cause you problems. But since you
haven't told us what happens in this failure case it is hard for us to
say, but,
if (-e blah_blah) {
unless (-d blah_blah) {
die File exists but is not directory;
}
}
else {
# don't forget to check mkdir's failure
mkdir(blah_blah, 0777) or die Can't make directory: $!;
}
HTH,
http://danconia.org
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Re: How to verify whether a directory exists
Wiggins D'Anconia wrote:
B. Fongo wrote:
I want to use mkdir(blah blah, o777), but want to first find out
whether the directory blah blah exists.
I'm not if the -e option will bw right here. Let's say:
unless (-e blah_blah) mkdir(blah_blah, 0777);
# Is this okay?
In general -e checks for file existence, -d checks to see if an existing
file is a directory (or complains that the file doesn't exist).
perldoc -f -e
So your above code leaves a condition, where blah_blah exists but is
*not* a directory which is likely to cause you problems. But since you
haven't told us what happens in this failure case it is hard for us to
say, but,
if (-e blah_blah) {
unless (-d blah_blah) {
die File exists but is not directory;
}
}
else {
# don't forget to check mkdir's failure
mkdir(blah_blah, 0777) or die Can't make directory: $!;
}
Just a note:
There's no need to do a separate -e call to check whether a directory
exists, -d won't throw an error. A simple
die $dir is not directory unless -d $dir;
Will check that $dir both exists and is a directory, which
is probably all that is needed.
Rob
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How to verify whether a directory exists
I want to use mkdir(blah blah, o777), but want to first find out whether the directory blah blah exists. I'm not if the -e option will bw right here. Let's say: unless (-e blah_blah) mkdir(blah_blah, 0777); # Is this okay? -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] http://learn.perl.org/ http://learn.perl.org/first-response
Re: How to verify whether a directory exists
Please don't cross post, if your question is CGI based then use that
list, otherwise use the other...
B. Fongo wrote:
I want to use mkdir(blah blah, o777), but want to first find out
whether the directory blah blah exists.
I'm not if the -e option will bw right here. Let's say:
unless (-e blah_blah) mkdir(blah_blah, 0777);
# Is this okay?
In general -e checks for file existence, -d checks to see if an existing
file is a directory (or complains that the file doesn't exist).
perldoc -f -e
So your above code leaves a condition, where blah_blah exists but is
*not* a directory which is likely to cause you problems. But since you
haven't told us what happens in this failure case it is hard for us to
say, but,
if (-e blah_blah) {
unless (-d blah_blah) {
die File exists but is not directory;
}
}
else {
# don't forget to check mkdir's failure
mkdir(blah_blah, 0777) or die Can't make directory: $!;
}
HTH,
http://danconia.org
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Re: How to verify whether a directory exists
On Dec 6, 2003, at 5:27 PM, B. Fongo wrote:
I want to use mkdir(blah blah, o777), but want to first find out
whether the directory blah blah exists.
I'm not if the -e option will bw right here. Let's say:
unless (-e blah_blah) mkdir(blah_blah, 0777);
# Is this okay?
May I recommend File::Path and it's mkpath()
for general useage...
that having been said, you might want to check
the return condition on your mkdir().
unless ( -e $dir )
{
$dir_test = mkdir($dir, 0777);
# code to handle the failed to mkdir here
}
ciao
drieux
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How to verify whether a directory exists
I want to use mkdir(blah blah, o777), but want to first find out whether the directory blah blah exists. I'm not if the -e option will bw right here. Let's say: unless (-e blah_blah) mkdir(blah_blah, 0777); # Is this okay? -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] http://learn.perl.org/ http://learn.perl.org/first-response
Re: How to verify whether a directory exists
Please don't cross post, if your question is CGI based then use that
list, otherwise use the other...
B. Fongo wrote:
I want to use mkdir(blah blah, o777), but want to first find out
whether the directory blah blah exists.
I'm not if the -e option will bw right here. Let's say:
unless (-e blah_blah) mkdir(blah_blah, 0777);
# Is this okay?
In general -e checks for file existence, -d checks to see if an existing
file is a directory (or complains that the file doesn't exist).
perldoc -f -e
So your above code leaves a condition, where blah_blah exists but is
*not* a directory which is likely to cause you problems. But since you
haven't told us what happens in this failure case it is hard for us to
say, but,
if (-e blah_blah) {
unless (-d blah_blah) {
die File exists but is not directory;
}
}
else {
# don't forget to check mkdir's failure
mkdir(blah_blah, 0777) or die Can't make directory: $!;
}
HTH,
http://danconia.org
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