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Posted by Etienne Marais on 12/07/05 03:51
Marty Meyers wrote:
> I have the following line in a php file:
>
> $msg= exec("perl $scriptPath/insert.pl $d $u $t 2>&1", $returnVal);
>
> Can someone explain the "2>&1" argument?
Error redirection.
&1 is stdout (standard output stream)
&2 is stderr (standard error stream)
if you do
command | more
and you get valid output, with lines of errors in between the output,
the errors are not piped to more and will mess up the display
unless you do:
command 2>&1 | more
which will work fine.
Or if you do
command > output.txt
output.txt does not contain any errors created(output) by command,
only the normal output of the command.
and
command 2> errors.txt
will contain only errors, none of the normal output.
You can do
command > output.txt 2> errors.txt
to get seperate output for normal and error reports
in two different files
command 2>&1 > output_and_errors.txt
to get all output into one report.
(Which places the errors in the same stream as the normal output,
and then redirects the normal output to output_and_errors.txt)
The reason your exec has 2>&1 is so
that the return value will contain any
possible errors and/or normal output.
If this was not added and if the
perl command should fail, you would
not even have that information in
returnVal.
>
> Second problem, this same line of code when run from the unix command line
> returns the following error:
>
> sh: /perl: No such file or directory
Just checking, are you saying that the
command works fine with:
$> perl insert.pl
but that it does not work from neither
php php_file_containg_exec.php
nor
$> perl $scriptPath/insert.pl $d $u $t 2>&1
Did you substitute $scriptPath; $d and $u with
the relevant values before trying this, or
exactly what did you do ?
--
Etienne Marais
Cosmic Link
South Africa
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