I am reading a text file.
One line from the text file looks like this and comes at the very end of the text file:
</DTS:Executable>
I am using replace("</DTS:Executable>","test from me")
Nothing gets replaced and the text stays as is.
What am I doing wrong?
What is the extension of the file ?
Can you try this sed command :
sed -i 's/original/new/g' file.txt
How about reading the data in list and replacing the last element, like so;
with open(fname) as f:
content = f.readlines()
lines = [line.rstrip('\n') for line in file]
lines[-1] = "test from me"
Did this work?
If the file content are not to large then straight forward you can do something like this
with open(filename) as f:
content = f.read()
content = content.replace("<old>", "<new>")
with open(filename, "w") as f:
f.write(content)
Related
I need to remove the following last two lines from my textfile:
ColorForeground=#000000
ColorBackground=#ffffff
The above lines are appended to the terminalrc file with the following command:
echo -e "ColorForeground=#000000\nColorBackground=#ffffff">>/home/jerzy/.config/xfce4/terminal/terminalrc
Thus, the last lines of the file to be modified look like this
DropdownKeepOpenDefault=TRUE
ColorForeground=#000000
ColorBackground=#ffffff
I wrote the following Python script in order to remove the last two lines of the file with .replace() method:
day = r"ColorForeground=#000000\nColorBackground=#ffffff"
file = r"/home/jerzy/.config/xfce4/terminal/terminalrc"
with open(file) as f:
content = f.read()
content = content.replace(day, "")
with open(file, 'r+') as f2:
f2.write(content)
Yet, my script does not work as expected. The following is the result of its execution:
DropdownKeepOpenDefault=TRUE
olorForeground=#000000
ColorBackground=#ffffff
Where is the error in my Python code? How would you write such a script? Is this task doable without using regular expressions?
Read and write seperately, also don't make day a raw string, that will escape the newline-
day = "ColorForeground=#000000\nColorBackground=#ffffff\n"
with open(file, 'r') as f:
content = f.read()
content = content.replace(day, "")
with open(file, 'w') as f:
f.write(content)
I have a text file that looks like this:
1,004,59
1,004,65
1,004,69
1,005,55
1,005,57
1,006,53
1,006,59
1,007,65
1,007,69
1,007,55
1,007,57
1,008,53
Want to create new text file that will be inserted by 'input', something like this
1,004,59,input
1,004,65,input
1,004,69,input
1,005,55,input
1,005,57,input
1,006,53,input
1,006,59,input
1,007,65,input
1,007,69,input
1,007,55,input
1,007,57,input
1,008,53,input
I have attempted something like this:
with open('data.txt', 'a') as f:
lines = f.readlines()
for i, line in enumerate(lines):
line[i] = line[i].strip() + 'input'
for line in lines:
f.writelines(line)
Not able to get the right approach though.
What you want is to be able to read and write to the file in place (at the same time). Python comes with the fileinput module which is good for this purpose:
import fileinput
for line in fileinput.input('data.txt', inplace=True):
line = line.rstrip()
print line + ",input"
Discusssion
The fileinput.input() function returns a generator that reads your file line by line. Each line ends up with a new line (either \n or \r\n, depends on the operating system).
The code then strip off each line of this new line, add the ",input" part, then print out. Note that because of fileinput magic, the print statement's output will go back into the file instead of the console.
There are a newline '\n' in every line in your file, so you should handle it.
edit: oh I forgot about the rstrip() function!
tmp = []
with open("input.txt", 'r') as file:
appendtext = ",input\n"
for line in file:
tmp.append(line.rstrip() + appendtext)
with open("input.txt", 'w') as file:
file.writelines(tmp)
Added:
Answer by Hai_Vu is great if you use fileinput since you don't have to open the file twice as I did.
To do only the thing you're asking I would go for something like
newLines = list()
with open('data.txt', 'r') as f:
lines = f.readlines()
for line in lines:
newLines.append(line.strip() + ',input\n')
with open('data2.txt', 'w') as f2:
f2.writelines(newLines)
But there are definitely more elegant solutions
I need some help Im trying to display the text files contents (foobar) with this code
text = open('C:\\Users\\Imran\\Desktop\\text.txt',"a")
rgb = text.write("foobar\n")
print (rgb)
text.close()
for some reason it keeps displaying a number. If anyone could help that would be awesome, thanks in advance
EDIT: I am Working with Python 3.3.
Print the contents of the file like this:
with open(filename) as f:
for line in f:
print(line)
Use with to ensure that the file handle will be closed when you are finished with it.
Append to the file like this:
with open(filename, 'a') as f:
f.write('some text')
# Open a file
fo = open("foo.txt", "r+")
str = fo.read();
print "Read String is : ", str
# Close opend file
fo.close()
More: http://www.tutorialspoint.com/python/python_files_io.htm
You are printing the number of written bytes. That won't work. Also you might need to open the file as RW.
Code:
text = open('...', "a")
text.write("foo\n")
text = open('...', "r")
print text.read()
If you want to display the contents of the file open it in read mode
f=open("PATH_TO_FILE", 'r')
And then print the contents of file using
for line in f:
print(line) # In Python3.
And yes, don't forget to close the file pointer f.close() after you finish the reading
I have an XML file that contains an illegal character, I am iterating through the file, removing the character from all of the lines and storing the lines in a list. I now want to write those same lines back into the file and overwrite what is already there.
I tried this:
file = open(filename, "r+")
#do stuff
Which is only appending the results to the end of the file, I would like to overwrite the existing file.
And this:
file = open(filename, "r")
#read from the file
file.close()
file = open(filename, "w")
#write to file
file.close()
This gives me a Bad File Descriptor error.
How can i read and write to the same file?
Thanks
You could re-write the lines list with writelines function.
with open(filename, "r") as f:
lines = f.readlines()
#edit lines here
with open(filename, "w") as f:
f.writelines(lines)
The reason you're appending to the end of the file the whole time is that you need to seek to the beginning of the file to write your lines out.
with open(filename, "r+") as file:
lines = file.readlines()
lines = [line.replace(bad_character, '') for line in lines]
file.seek(0)
file.writelines(lines)
file.truncate() # Will get rid of any excess characters left at the end of the file due to the length of your new file being shorter than the old one, as you've removed characters.
(Decided to just use the context manager syntax myself.)
I am trying to form a quotes file of a specific user name in a log file. How do I remove every line that does not contain the specific user name in it? Or how do I write all the lines which contain this user name to a new file?
with open('input.txt', 'r') as rfp:
with open('output.txt', 'w') as wfp:
for line in rfp:
if ilikethis(line):
wfp.write(line)
with open(logfile) as f_in:
lines = [l for l in f_in if username in l]
with open(outfile, 'w') as f_out:
f_out.writelines(lines)
Or if you don't want to store all the lines in memory
with open(logfile) as f_in:
lines = (l for l in f_in if username in l)
with open(outfile, 'w') as f_out:
f_out.writelines(lines)
I sort of like the first one better but for a large file, it might drag.
Something along this line should suffice:
newfile = open(newfilename, 'w')
for line in file(filename, 'r'):
if name in line:
newfile.write(line)
newfile.close()
See : http://docs.python.org/tutorial/inputoutput.html#methods-of-file-objects
f.readlines() returns a list containing all the lines of data in the file.
An alternative approach to reading lines is to loop over the file object. This is memory efficient, fast, and leads to simpler code
>>> for line in f:
print line
Also you can checkout the use of with keyword. The advantage that the file is properly closed after its suite finishes
>>> with open(filename, 'r') as f:
... read_data = f.read()
>>> f.closed
True
I know you asked for python, but if you're on unix this is a job for grep.
grep name file
If you're not on unix, well... the answer above does the trick :)