Python development masterclass

File search
File search is essential to any system administration task. In this section we will build a Python file search script which will search for files based on the given pattern(s) and will also return the file permissions. Like the earlier program, this script will also make use of the commands module to issue the UNIX command ‘find’. We will also make use of a Python module called ‘stat’ to fetch the permissions information.

Code for: filesearch.py

@description: file pattern search script

import stat, sys, os, string, commands

pattern = raw_input(“Enter the file pattern to search for:\n”)
command = “find “ + pattern
output = commands.getoutput(command)
findResults = string.split(output, “\n”)

print “Found Files:”
print output
print “================================”
for file in findResults:
 mode=stat.S_IMODE(os.lstat(file)[stat.ST_MODE])
 print “\nPermissions for file “, file, “:”
 for level in “USR”, “GRP”, “OTH”:
 for perm in “R”, “W”, “X”:
 if mode & getattr(stat,”S_I”+perm+level):
 print level, “ has “, perm, “ permission”
 else:
 print level, “ does NOT have “, perm, “ permission”
@code ends

@output
kunaldeo$ python filesearch.py
Enter the file pattern to search for:
*.py
Found Files:
filesearch.py
py.py

Permissions for filesearch.py

USR  has  R  permission
USR  has  W  permission
USR  does NOT have  X  permission
GRP  has  R  permission
GRP  does NOT have  W  permission
GRP  does NOT have  X  permission
OTH  has  R  permission
OTH  does NOT have  W  permission
OTH  does NOT have  X  permission

Permissions for py.py

USR  has  R  permission
USR  has  W  permission
USR  does NOT have  X  permission
GRP  has  R  permission
GRP  does NOT have  W  permission
GRP  does NOT have  X  permission
OTH  has  R  permission
OTH  does NOT have  W  permission
OTH  does NOT have  X  permission

So now you have an idea of how to use Python in system administration tasks. The following is a list of Python modules that may be of interest to system administrators…
commands: Utility functions for running external commands.
stat: Utilities for interpreting the results of os.stat(), os.lstat() and os.fstat() – in other words, it helps process the permissions.
sys: Access system-specific parameters and functions.
os: Functions to access operations on pathnames.
string: Functions for common string operations.
tty: Utility functions that perform common terminal control operations.
syslog: An interface to the UNIX syslog library routines.

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