python write - How do you append to a file?
new line (7)
with open("test.txt", "a") as myfile: myfile.write("appended text")
How do you append to the file instead of overwriting it? Is there a special function that appends to the file?
You probably want to pass
"a" as the mode argument. See the docs for open().
with open("foo", "a") as f: f.write("cool beans...")
There are other permutations of the mode argument for updating (+), truncating (w) and binary (b) mode but starting with just
"a" is your best bet.
Python has many variations off of the main three modes, these three modes are:
'w' write text 'r' read text 'a' append text
So to append to a file it's as easy as:
f = open('filename.txt', 'a') f.write('whatever you want to write here (in append mode) here.')
Then there are the modes that just make your code fewer lines:
'r+' read + write text 'w+' read + write text 'a+' append + read text
Finally, there are the modes of reading/writing in binary format:
'rb' read binary 'wb' write binary 'ab' append binary 'rb+' read + write binary 'wb+' read + write binary 'ab+' append + read binary
when we using this line
open(filename, "a"), that
a indicates the appending the file, that means allow to insert extra data to the existing file.
You can just use this following lines to append the text in your file
def FileSave(filename,content): with open(filename, "a") as myfile: myfile.write(content) FileSave("test.txt","test1 \n") FileSave("test.txt","test2 \n")
Here's my script, which basically counts the number of lines, then appends, then counts them again so you have evidence it worked.
shortPath = "../file_to_be_appended" short = open(shortPath, 'r') ## this counts how many line are originally in the file: long_path = "../file_to_be_appended_to" long = open(long_path, 'r') for i,l in enumerate(long): pass print "%s has %i lines initially" %(long_path,i) long.close() long = open(long_path, 'a') ## now open long file to append l = True ## will be a line c = 0 ## count the number of lines you write while l: try: l = short.next() ## when you run out of lines, this breaks and the except statement is run c += 1 long.write(l) except: l = None long.close() print "Done!, wrote %s lines" %c ## finally, count how many lines are left. long = open(long_path, 'r') for i,l in enumerate(long): pass print "%s has %i lines after appending new lines" %(long_path, i) long.close()
I always do this,
f = open('filename.txt', 'a') f.write("stuff") f.close()
It's simple, but very useful.
You can use one of the copy functions from the
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Function preserves supports accepts copies other permissions directory dest. file obj metadata ―――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――― shutil.copy ✔ ✔ ☐ ☐ shutil.copy2 ✔ ✔ ☐ ✔ shutil.copyfile ☐ ☐ ☐ ☐ shutil.copyfileobj ☐ ☐ ✔ ☐ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
import shutil shutil.copy('/etc/hostname', '/var/tmp/testhostname')