问题
How to get the result on another file after applying diff to file A.txt and B.txt.
Suppose File A.txt has:
a
b
c
File B.txt has:
a
b
on running
diff A.txt B.txt It gives result as c, but how to store it in a file C.txt?
回答1:
The diff utility produces its output on standard output (usually the console). Like any UNIX utility that does this, its output may very simply be redirected into a file like this:
diff A.txt B.txt >C.txt
This means "execute the command diff with two arguments (the files A.txt and B.txt) and put everything that would otherwise be displayed on the console into the file C.txt". Error messages will still go to the console.
To save the output of diff to a file and also send it to the terminal, use tee like so:
diff A.txt B.txt | tee C.txt
tee will duplicate the data to all named files (only C.txt here) and also to standard output (most likely the terminal).
回答2:
Using > you can redirect output to a file. Eg:
diff A.txt B.txt > C.txt
This will result in the output from the diff command being saved in a file called C.txt.
回答3:
Use Output Redirection.
diff file1 file2 > output
will store the diff of file1 and file2 to output
回答4:
There are some files that diff may not do well with the output, like block special files, character special files, and broken links. The output due to differences with these may go to standard error.
Interestingly, when I redirected standard error, I still missed some things:
diff -qr <DirA> <DirB> 2>&1 > mydiff.txt
The only way to see the results of everything was to:
diff -qr <DirA> <DirB> |tee mydiff.txt
I was comparing the results of a live-cd mounted directory after copying to an external HD
来源：https://stackoverflow.com/questions/7732545/how-to-store-result-of-diff-in-linux