Ok, well you're going about that all wrong. To execute an external program and get its output into an array of lines, use qx():

@fields = qx( /opt/apache/1.3.27/cgi-bin/cspireutils/ldapsearch -h 172
+.30.58.243 -p 389 -D $dirsrv -w 'passwd' -b ou=subscribers,ou=users,o
+u=prague,ou=domains,ou=cz,ou=domains,o=chello cn=$sid dn jrMailBoxId 
+jrMailboxAliasStore jrPWPUID jrPWPUserPrefs jrUserFriendlyID );
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then you can easily iterate over the lines with foreach.

Alternatively, you could use the while(<>) construct to read from a pipe connected to the output of an external program:

open P, $command  # as above
  or die "can't run $command - $!";
while (<P>)
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but note specially the use of an explicit filehandle inside the angle brackets. Omit that, and you'd be reading from stdin.

If you assign to @fields as above, you'll be overwriting the array of values you orginally assigned to it. Is that what you intended?