how to invoke unix command in perl

Question

i am trying to execute following unix command but its not getting executed

$array_of_tables= `dbsmp $srv_name`;
print "$array_of_tables\n";

please help me to find out list of tables in a data base through perl scripting.

Also i am trying to copy a file from a path to different path by using following command:-

copy(`cd /osp/slee/service/$srv_name/bin/exec/script.txt`,`cd /osp/local/home/linus/amit/scripts`);

but getting an error:-

Usage: copy(FROM, TO [, BUFFERSIZE])

please provide some solution Thanks

Your second command should simply be copy('/osp/.../script.txt', '/osp/.../scripts'); (note the apostrophes are not backticks) — knittl
– knittl, Commented Jan 8, 2015 at 6:52
Just don't invoke external commands and use robust and portable core modules, perldoc.perl.org/File/Copy.html — mpapec
– mpapec, Commented Jan 8, 2015 at 6:55

Jens · Accepted Answer · 2015-01-08 07:46:32Z

3

Use doublequotes instead of back ticks.

copy("/osp/slee/service/$srv_name/bin/exec/script.txt","/osp/local/home/linus/amit/scripts");

and remove the cd

edited Jan 8, 2015 at 7:46

answered Jan 8, 2015 at 6:52

Jens

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Amit Over a year ago

Now i am not getting that particular error but file is not getting copied at the given path. Is there any other method to copy a file at unix platform in perl scripting ?

bgoldst · Accepted Answer · 2015-01-08 07:03:43Z

0

In Perl, the preferable way to capture the output of a system (shell) command is the qx() operator. See http://perldoc.perl.org/perlop.html#Quote-Like-Operators.

$array_of_tables = qx(dbsmp $srv_name);
print("$array_of_tables\n");

Actually, backticks should also work, so the problem must lie with your dbsmp command. I'm not sure what that command is; you'll have to provide more information about the utility and what error you're seeing.

For comparison, I can retrieve the list of tables in my local postgres database as a pipe-separated table using this shell command:

> psql -tAXq main postgres <<<\\d;

And this can be run from Perl as follows:

> perl -e 'print(qx(psql -tAXq main postgres <<<\\\\d;));'

edited Jan 8, 2015 at 7:03

answered Jan 8, 2015 at 6:55

bgoldst

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1 Comment

ysth Over a year ago

backticks are the qx operator (just like double quotes are qq and single quotes are q)

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