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#!/usr/bin/python3
#
# This is a helper tool for editing configuration files during the setup
# process. The tool is given new values for settings as command-line
# arguments. It comments-out existing setting values in the configuration
# file and adds new values either after their former location or at the
# end.
#
# The configuration file has settings that look like:
#
# NAME=VALUE
#
# If the -s option is given, then space becomes the delimiter, i.e.:
#
# NAME VALUE
#
# If the -w option is given, then setting lines continue onto following
# lines while the lines start with whitespace, e.g.:
#
# NAME VAL
# UE
import sys, re
# sanity check
if len(sys.argv) < 3:
print("usage: python3 editconf.py /etc/file.conf [-s] [-w] [-t] NAME=VAL [NAME=VAL ...]")
sys.exit(1)
# parse command line arguments
filename = sys.argv[1]
settings = sys.argv[2:]
delimiter = "="
delimiter_re = r"\s*=\s*"
comment_char = "#"
folded_lines = False
testing = False
while settings[0][0] == "-" and settings[0] != "--":
opt = settings.pop(0)
if opt == "-s":
# Space is the delimiter
delimiter = " "
delimiter_re = r"\s+"
elif opt == "-w":
# Line folding is possible in this file.
folded_lines = True
elif opt == "-c":
# Specifies a different comment character.
comment_char = settings.pop(0)
elif opt == "-t":
testing = True
else:
print("Invalid option.")
sys.exit(1)
# create the new config file in memory
found = set()
buf = ""
input_lines = list(open(filename))
while len(input_lines) > 0:
line = input_lines.pop(0)
# If this configuration file uses folded lines, append any folded lines
# into our input buffer.
if folded_lines and line[0] not in (comment_char, " ", ""):
while len(input_lines) > 0 and input_lines[0][0] in " \t":
line += input_lines.pop(0)
# See if this line is for any settings passed on the command line.
for i in range(len(settings)):
# Check that this line contain this setting from the command-line arguments.
name, val = settings[i].split("=", 1)
m = re.match(
"(\s*)"
+ "(" + re.escape(comment_char) + "\s*)?"
+ re.escape(name) + delimiter_re + "(.*?)\s*$",
line, re.S)
if not m: continue
indent, is_comment, existing_val = m.groups()
# If this is already the setting, do nothing.
if is_comment is None and existing_val == val:
# It may be that we've already inserted this setting higher
# in the file so check for that first.
if i in found: break
buf += line
found.add(i)
break
# comment-out the existing line (also comment any folded lines)
if is_comment is None:
buf += comment_char + line.rstrip().replace("\n", "\n" + comment_char) + "\n"
else:
# the line is already commented, pass it through
buf += line
# if this option oddly appears more than once, don't add the setting again
if i in found:
break
# add the new setting
buf += indent + name + delimiter + val + "\n"
# note that we've applied this option
found.add(i)
break
else:
# If did not match any setting names, pass this line through.
buf += line
# Put any settings we didn't see at the end of the file.
for i in range(len(settings)):
if i not in found:
name, val = settings[i].split("=", 1)
buf += name + delimiter + val + "\n"
if not testing:
# Write out the new file.
with open(filename, "w") as f:
f.write(buf)
else:
# Just print the new file to stdout.
print(buf)