Question about the %ENV hash 1

[nfaber]

Morning all,

I have a question about using the %ENV hash. I have a script I wrote that runs as a cron job. While the script runs fine from the command line, it does not as a cron because it does not have all the correct shell ENV variables, in this case $ORACLE_HOME and $ORACLE_SID. What I have done in the past is create a shell script wrapper that runs my script as in:

export ORACLE_SID = mysid
export ORACLE_HOME = opt/my/oracle

# Then run my script

/local/bin/my_perl_script.pl

While this works, I would like to not have to create my wrapper and do it all in my script. I know I can get the variable in my script with:

my $ORACLE_HOME = $ENV{ORACLE_HOME};

Is that all I need to do? If so (or if not for that matter), how does the shell my script runs under get this var?

Thanks,

Nick

 

[mikevh]

Is there some reason your Perl script can't set these vars, e.g.

$ENV{ORACLE_SID} = whatever;
$ENV{ORACLE_HOME} = 'opt/my/oracle'

 

[nfaber]

Thanks for the reply Mike. When I print the %ENV hash, the ORACLE ENVs are there and correct, so I assume my script can see it?

The statements you have would actually change the system ENV variable would it not? as in:

Say the SID is "whatelse" normally (set in the .profile for instance).

if I ran the statement:

$ENV{ORACLE_SID} = whatever;

Would't the system SID now be whatever?

 

[mikevh]

It will be changed only for the life of the Perl script. When the script terminates, it'll be back to "normal."

 

[nfaber]

Thanks Mike. That brings me back to my original question though. This is what I do right now when I need to run my scripts as a cron job:

Run the Unix "env" command, pipe it to a file and put an "export" in front of each env var in the file and then run my script as the last command.

This is not a good way to do it. If nothing else, the next time a path variable changes during an application upgrade, my script no longer works if the app home changes from something like:

/opt/app56 (version number)

to

/opt/app57

The web tuts on the ENV hash do not explain this well.

As always,

Nick

I got a Biz Degree! How the h*ll did I get here?

 

[arn0ld]

your problem is not a perl issue, it is a cron issue.
cron sets only a few environment variables. perl simply takes the current environment the script is running under and puts it into %ENV.

any command/script run under cron is responsible for setting the "correct" environment variables. even us comp science types sweat missing environment at the 1st run of a cron script.

usually, i first run a test script scheduled a few minutes in the future and pipe debugging output (eg: map { print "$ENV{$_}, $_\n"}keys %ENV ) to a file - or it will be sent as mail by cron.

BTW, "export ORACLE_HOME = opt/my/oracle" is a typo?