Perl Syntax
I'm using perl 5.8.4 on a 4.9 machine. I want to add code a perl script
to check for value passed from command line. If it is null, I want to
exit with an error message.
First I tried this and got Use of uninitialized value in string eq at
./test.pl line 20.
if ($ARGV[0] eq ) {
print You must include the file name.;
exit 1;
}
Next I tried this but get Use of uninitialized value in length at
./test.pl line 20.
if (length ($ARGV[0]) = 0) {
print You must include the file name.;
exit 1;
}
I've searched the web and all examples that I've found indicate that I'm
doing things correctly but obviously I'm not. What am I doing wrong?
Thanks,
Drew
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Re: Perl Syntax
I'm using perl 5.8.4 on a 4.9 machine. I want to add code a perl script
to check for value passed from command line. If it is null, I want to
exit with an error message.
First I tried this and got Use of uninitialized value in string eq at
./test.pl line 20.
if ($ARGV[0] eq ) {
print You must include the file name.;
exit 1;
}
Next I tried this but get Use of uninitialized value in length at
./test.pl line 20.
if (length ($ARGV[0]) = 0) {
print You must include the file name.;
exit 1;
}
I've searched the web and all examples that I've found indicate that I'm
doing things correctly but obviously I'm not. What am I doing wrong?
I know this works:
if ($ARGV[0] eq '') {
print Debug Mode\n;
}
Cheers,
Steve
Thanks,
Drew
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Re: Perl Syntax
On 6/30/2004 10:04 AM Steve Bertrand wrote:
I'm using perl 5.8.4 on a 4.9 machine. I want to add code a perl script
to check for value passed from command line. If it is null, I want to
exit with an error message.
First I tried this and got Use of uninitialized value in string eq at
./test.pl line 20.
if ($ARGV[0] eq ) {
print You must include the file name.;
exit 1;
}
Next I tried this but get Use of uninitialized value in length at
./test.pl line 20.
if (length ($ARGV[0]) = 0) {
print You must include the file name.;
exit 1;
}
I've searched the web and all examples that I've found indicate that I'm
doing things correctly but obviously I'm not. What am I doing wrong?
I know this works:
if ($ARGV[0] eq '') {
print Debug Mode\n;
}
Cheers,
Steve
Thanks for your reply. I tried your suggestion and it seems to work but
I get this output:
Use of uninitialized value in string eq at ./test.pl line 16.
You must include the file name.
I have use warnings; and use strict; in the script. I assume the
error comes from the use warnings; but why does perl see eq as a
string and not an operator? Or am I misinterpreting the message?
Thanks,
Drew
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Re: Perl Syntax
On Wed, Jun 30, 2004 at 10:17:45AM -0700, Drew Tomlinson wrote:
On 6/30/2004 10:04 AM Steve Bertrand wrote:
I know this works:
if ($ARGV[0] eq '') {
print Debug Mode\n;
}
Thanks for your reply. I tried your suggestion and it seems to work but
I get this output:
Use of uninitialized value in string eq at ./test.pl line 16.
You must include the file name.
Unless you supply at least one argument to the script, $ARGV[0] won't
exist. There's a difference in perl between 'not defined' and an
empty string (or zero for numerical values). Try:
if ( @ARGV 1 ) {
usage();
exit 1;
}
or
unless ( defined $ARGV[0] ) {
usage();
exit 1;
}
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Re: Perl Syntax
I'm using perl 5.8.4 on a 4.9 machine. I want to add code a perl script
to check for value passed from command line. If it is null, I want to
exit with an error message.
First I tried this and got Use of uninitialized value in string eq at
./test.pl line 20.
if ($ARGV[0] eq ) {
print You must include the file name.;
exit 1;
}
Next I tried this but get Use of uninitialized value in length at
./test.pl line 20.
if (length ($ARGV[0]) = 0) {
print You must include the file name.;
exit 1;
}
I've searched the web and all examples that I've found indicate that I'm
doing things correctly but obviously I'm not. What am I doing wrong?
I know this works:
if ($ARGV[0] eq '') {
print Debug Mode\n;
}
Cheers,
Steve
Thanks for your reply. I tried your suggestion and it seems to work but
I get this output:
Use of uninitialized value in string eq at ./test.pl line 16.
You must include the file name.
I have use warnings; and use strict; in the script. I assume the
error comes from the use warnings; but why does perl see eq as a
string and not an operator? Or am I misinterpreting the message?
Thanks,
Drew
#!/usr/bin/perl -w
if (!ARGV[0]) {
print no arguements\n;
}
else {
print found an arguement\n;
}
Josh Paetzel
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Re: Perl Syntax -- SOLVED
On 6/30/2004 10:34 AM Matthew Seaman wrote:
On Wed, Jun 30, 2004 at 10:17:45AM -0700, Drew Tomlinson wrote:
On 6/30/2004 10:04 AM Steve Bertrand wrote:
I know this works:
if ($ARGV[0] eq '') {
print Debug Mode\n;
}
Thanks for your reply. I tried your suggestion and it seems to work but
I get this output:
Use of uninitialized value in string eq at ./test.pl line 16.
You must include the file name.
Unless you supply at least one argument to the script, $ARGV[0] won't
exist. There's a difference in perl between 'not defined' and an
empty string (or zero for numerical values). Try:
if ( @ARGV 1 ) {
usage();
exit 1;
}
or
unless ( defined $ARGV[0] ) {
usage();
exit 1;
}
Thank you very much for the explanation. Now I understand why I was
getting the error message. I didn't quite understand how to use
usage(); but replaced it with a print statement. It works perfectly!
Thanks,
Drew
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