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PHP execute UNIX command

Posted on 2009-06-29
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Last Modified: 2013-12-13
I am want to use PHP to 'exec' a pgp encryption command. Regardless of the command line I get either a err 64 (parser error) or 162 (complete failure during an encode). So I have reduced the command line within the PHP program to:

exec("/opt/pgp/bin/pgp --fingerprint", $results);

If I run "/opt/pgp/bin/pgp --fingerprint" on a command line I get "2 keys found" and the expected display. But the same exec under PHP gives me the parser error 64. I have tried "\n" to the string command and that does not make a difference. The user runs as 'nobody' in the browser which does have execute permission. If pgp was not at least starting up I would not even see the 'parser error' from it.

Is there something special I need to do in order to run pgp under PHP?

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Question by:esc_toe_account
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Expert Comment

by:Michal-Drozd
ID: 24741152
try following (replace " with ') :
exec('/opt/pgp/bin/pgp --fingerprint', $results);

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Author Comment

by:esc_toe_account
ID: 24750009
Thanks for responding.

SIngle versus double quotes do not make a difference. I have gotten --fingerprint to work and the key was setting the environment variable PGP_HOME_DIR.
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Author Comment

by:esc_toe_account
ID: 24750033
With that one small step forward I have returned to the original problem which is getting pgp to actrually encrypt a file running as a shell command from PHP called by a browser. The exec() command is:

/opt/pgp/bin/pgp --encrypt /export/home/eckankar/dev/inc/test.txt -r 'membership' --overwrite remove --home-dir /export/home/pgphome/.pgp -v --status-file /export/home/eckankar/dev/inc/test.txt.err

 The command runs fine if I run it on the unix command line; it also runs fine if I run the php script from a command line (which in turn will shell out to exec(pgp).....); it also runs fine if a browser executes a perl script which shells out to the pgp command. However when I run it from the browser, calling PHP, I get a permission denied error shown on the last line of the status-file as follows:

pgp:encrypt (3157:current local time 2009-06-30T07:41:18-05:00)
/export/home/pgphome/.pgp/pubring.pkr : open keyrings (1006 : public keyring)
/export/home/pgphome/.pgp/secring.skr : open keyrings (1007 : private keyring)
0x221DC947:encrypt (1030 : key added to recipient list)
/export/home/eckankar/dev/inc/test.txt:encrypt (3048 : data encrypted with cipher AES-128)
/export/home/eckankar/dev/inc/test.txt:encrypt (3124 : permission denied)

So the question is: what permission is being denied?

It most certainly is not test.txt, the input file. It obviously reads it and encrypts the data so that permission is fine. Further, I set its permission for the world as 'wr'. The output file, going to the same directory as the input file with a .pgp extension, should not be a problem either as that folder is set to world 'rw'. Since pgp creates the status file shown above (in the same folder) there can't be a permission issue with that folder.

The issue is almost certainly a permission associated with the user. The browser runs as 'nobody' which has almost no environment variables and very few permissions. (Note the perl script runs fine as 'nobody'!) But as a member of 'world/other' it does have 'rw' to all the folders it requires. So can anyone suggest what permission might be needed here?
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Accepted Solution

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Michal-Drozd earned 500 total points
ID: 24750332
Perhaps i found the solution to this. It appears apache is using a working folder where it isn't an owner or isn't part of pgp's working folder. This is usually the site's current working folder - the folder where the web page was loaded.

To get this to work always set --temp-dir to the same folder where the encryption takes place.
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Author Closing Comment

by:esc_toe_account
ID: 31598575
Good work Michal-Drozd - that was indeed the solution..
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