I need to search for a certain parameter known as jvm_args in a configuration file known as config.ini
**contents of config.ini:
first_paramter=some_value1
second_parameter=some_value2
jvm_args=some_value3**
I need to know how to find this parameter in my file and append something to its value, (i.e append a string to the string some_value3).
If you "just" want to find keys and values in an ini file, I think the configparser module is a better bet than using regexps. The configparser asserts that the file has "sections", though.
Documentation for configparser is here: http://docs.python.org/library/configparser.html - useful examples at the bottom. The configparser can also be used for setting values and writing out a new .ini-file.
Input file:
$ cat /tmp/foo.ini
[some_section]
first_paramter = some_value1
second_parameter = some_value2
jvm_args = some_value3
Code:
#!/usr/bin/python3
import configparser
config = configparser.ConfigParser()
config.read("/tmp/foo.ini")
jvm_args = config.get('some_section', 'jvm_args')
print("jvm_args was: %s" % jvm_args)
config.set('some_section', 'jvm_args', jvm_args + ' some_value4')
with open("/tmp/foo.ini", "w") as fp:
config.write(fp)
Output file:
$ cat /tmp/foo.ini
[some_section]
first_paramter = some_value1
second_parameter = some_value2
jvm_args = some_value3 some_value4
You can use re.sub
import re
import os
file = open('config.ini')
new_file = open('new_config.ini', 'w')
for line in file:
new_file.write(re.sub(r'(jvm_args)\s*=\s*(\w+)', r'\1=\2hello', line))
file.close()
new_file.close()
os.remove('config.ini')
os.rename('new_config.ini', 'config.ini')
also check ConfigParser
As both avasal and tobixen have suggested, you can use the python ConfigParser module to do this. For example, I took this "config.ini" file:
[section]
framter = some_value1
second_parameter = some_value2
jvm_args = some_value3**
and ran this python script:
import ConfigParser
p = ConfigParser.ConfigParser()
p.read("config.ini")
p.set("section", "jvm_args", p.get("section", "jvm_args") + "stuff")
with open("config.ini", "w") as f:
p.write(f)
and the contents of the "config.ini" file after running the script was:
[section]
framter = some_value1
second_parameter = some_value2
jvm_args = some_value3**stuff
without regex you can try:
with open('data1.txt','r') as f:
x,replace=f.read(),'new_entry'
ind=x.index('jvm_args=')+len('jvm_args=')
end=x.find('\n',ind) if x.find('\n',ind)!=-1 else x.rfind('',ind)
x=x.replace(x[ind:end],replace)
with open('data1.txt','w') as f:
f.write(x)
