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Full Discussion: Sourcing Env file with eval works with ksh but not BASH
Top Forums Shell Programming and Scripting Sourcing Env file with eval works with ksh but not BASH Post 302953935 by waavman on Wednesday 2nd of September 2015 05:47:59 PM
Old 09-02-2015
Hi Don,

I am using perl script to read the envfile because eventually I would like this shell script to be used by other users who donot even have read access to /tmp/envfile.txt (using setuid bit that Perl supports)
For now however the userid that this is being run with does have read access to /tmp/envfile.txt. Or else it would not have worked even with KSH.

I tried using eval with cat instead of the perl script as you suggested.
But I notice the same behaviour as shown below.

Code:
#!/bin/bash
#eval `/tmp/filereader.pl /tmp/envfile.txt` 
eval $(cat /tmp/envfile.txt)
echo "TESTPATH=$TESTPATH"


And I get the following INCORRECT output where $BASEPATH is not substituted in the value of $TESTPATH
--------------------------------------------------------
TESTPATH=/subdir

But when I change shebang to #!/bin/ksh as below

Code:
#!/bin/ksh
#eval `/tmp/filereader.pl /tmp/envfile.txt` 
eval $(cat /tmp/envfile.txt)
echo "TESTPATH=$TESTPATH"


I get the correct output
---------------------------
TESTPATH=/masterdir/subdir

I tried adding TESTPATH=before before the eval `perlfile...` and also before eval $(cat...). It doesnot use that value of TESTPATH since it overwrites it with the value of TESTPATH from the /tmp/envfile.txt in both KSH and BASH.

As for my perl script /tmp/filereader.pl its a simple script that just reads form the input file argument and prints one line at a time

Code:
#!/usr/bin/suidperl
$envfilename=$ARGV[0];
open(FILEHANDLE,"<$envfilename") || die "Cannot Open file $envfilename";
while (<FILEHANDLE>)
{
        $lineread=$_;
        chop($lineread);
        printf("%s\n",$lineread);
}

However as you can see it does NOT seem to be an issue with the Perl script since the same variation of behaviour is exhibited between bash and ksh even when using eval $(cat /tmp/envfile.txt)


thanks
waavman
 

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LEARN ABOUT MOJAVE

pam_env

pam_env(8)						    BSD System Manager's Manual 						pam_env(8)

NAME

     pam_env -- The Environment PAM module

SYNOPSIS

     [service-name] function-class control-flag pam_env [options]

DESCRIPTION

     The Environment PAM module supports the authentication and session management function classes.  In terms of the function-class parameter,
     these are ``auth'' and ``session'' respectively.  The Environment PAM module has identical support for both supported function classes.

     The Environment PAM module allows the setting and unsetting of environment variables.  The use of previously set environment variables as
     well as PAM_ITEMs such as PAM_RHOST is supported.

     This module can also parse a file with simple KEY=VAL pairs on separate lines (/etc/environment by default).  You can change the default file
     to parse, with the envfile flag and turn it on or off by setting the readenv flag to 1 or 0 respectively.

     The following options may be passed to this module:

     conffile=/path/to/pam_env.conf
		 Indicate an alternative pam_env.conf style configuration file to override the default. This can be useful when different services
		 need different environments.

     debug	 A lot of debug information will be printed to the system log.

     envfile=/path/to/environment
		 Indicate an alternative environment file to override the default. This can be useful when different services need different envi-
		 ronments.

     readenv=0|1
		 Turns on or off the reading of the file specified by envfile (0 is off, 1 is on). By default this option is on.

FILES

     /etc/security/pam_env.conf        The default configuration file.

     /etc/environment		       The default environment file.

SEE ALSO

     environ(7), pam.conf(5), pam(8)

AUTHORS

     The pam_env module was written by Dave Kinchlea <kinch@kinch.ark.com>.

BSD
								 February 7, 2009							       BSD
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