Deleting last line of a file

Question

I want to delete last line of a file on a particular condition. I used sed and cut but they work only on the output stream but I want to do this in the file. Can someone help me? Thanks in advance.

Answer 1

sed -ie '$d' filename.txt

i选项告诉sed编辑文件。

Answer 2

I'll use a variant on another answer and suggest a simple use of ed:

ed tmp.tmp << EOC
$
d
w
q
EOC

Otherwise you can use sed/cut to a temporary file and mv to overwrite the starting file.

Answer 3

You can always do:

cat * > out

Where you could remove 'cat *' with whatever you're doing, and the out is the result of that command.

I can take a more thorough look if you provide more information on what you're trying to do.