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Linux System Administration
book

Linux System Administration

by Tom Adelstein, Bill Lubanovic
March 2007
Intermediate to advanced content levelIntermediate to advanced
304 pages
11h 12m
English
O'Reilly Media, Inc.
Content preview from Linux System Administration
Scripting Language Shootout
|
233
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 ...
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Publisher Resources

ISBN: 9780596009526Supplemental ContentCatalog PageErrata