Linux System Administration

Scripting Language Shootout

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But can we call a function like Perl’s getpwent to slice and dice the password file for

us? PHP doesn’t appear to have an equivalent, so we’ll stick with the parsing

approach to restrict the search to uid values over 500:

#!/usr/bin/php

<?

$pattern = $argv[1];

$file = fopen("/etc/passwd", "r");

while ($line = fgets($file, 200)) {

$fields = split(":", $line);

if (eregi($pattern, $fields[4]) and $fields[2] > 500)

echo $line;

}

fclose($file);

?>

The Python script

Python scripts look different from Perl and PHP scripts, because statements are ter-

minated with whitespace rather than C-style semicolons or curly braces. Tab charac-

ters are also significant. Our first Python script, like our earlier attempts in the other

languages, searches the password file and prints any line that contains the matching

text:

#!/usr/bin/python

import re, sys

pattern = "(?i)" + sys.argv[1]

file = open("/etc/passwd")

for line in file:

if re.search(pattern, line):

print line

Python has namespaces (as does Perl) to group functions, which is why the functions

in this script are preceded by the strings

sys. and re.. This helps keep code modules

a little more, well, modular. The

"(?i)" in the third line of the script makes the

match case-insensitive, similar to

/i in Perl.

The next iteration, which splits the input line into fields, involves a straightforward

addition to the first:

#!/usr/bin/python

import ...