调整perl脚本以从cgi运行

Question

I have a perl script which works fine from shell but doesn't work from web (lighttpd + mod_cgi). I found out that problem is with the following string

my $lastupdate = `/opt/mongo/bin/mongo 127.0.0.1:27117/getVersion -u test -p test --eval 'db.polling.find({},{"_id":0,"host":0,"ports":0}).sort({"date":-1}).limit(1).forEach(function(x){printjson(x)})' | awk -F'"' '/date/{print \$4}' |sed 's/T/,/;s/Z//'`;

As i understood, when running from cgi, string is not being splitted. So i have done this by my own

my $lastupdate = system('/opt/mongo/bin/mongo', '127.0.0.1:27117/getVersion', '-u', 'test', '-p', 'test', '--eval', 'db.polling.find({},{"_id":0,"host":0,"ports":0}).sort({"date":-1}).limit(1).forEach(function(x){printjson(x)})', '|', 'awk', '-F', '"', '/date/{print', '\$4}', '|sed', 's/T/,/;s/Z//');

Script works now but gives me unexpected value (differs from shell's run value).
What did i miss?
PS I know that there are smarter ways to interact mongoDB from perl, but my env is totally firewalled. I have access neither to CPAN, nor to rh repos and perl mongoDB driver has too much deps to install it manually.

Answer 1

The environment that you run a program under from a shell is completely different to the environment that the same program gets when run from a web server. Most obviously, it will be run as a different user - one who will have far more restricted filesystem permissions that the average user.

You can (partly) simulate this by working out which user your web server runs as (perhaps apache, www or nobody) and using sudo to run your program as that user. This might well reveal what the problem is.

You can't just switch from backticks to system() . Backticks return the output from running the command line and system() returns a value which requires some interpretation . That'll be why you're seeing a different result.