What's the difference between using > and >> in shell?

Question

I've seen somewhere that we can use >> in shell. What's the difference between using > and >> in shell?

Answer 1

>> is for appending whereas > is for writing (replacing).

Answer 2

There is a difference if the file you're redirecting to already exists:

> truncates (i.e. replaces) an existing file.

>> appends to the existing file.

Answer 3

If the file exists, >> will append to the end of the file, > will overwrite it.

Both will create it otherwise.

Answer 4

'>>' will let you append data to a file, where '>' will overwrite it. For example:

# cat test
test file
# echo test > test
# cat test
test
# echo file >> test
# cat test
test
file

Answer 5

When you use >, as in:

$ echo "this is a test" > output.txt

The > operator will completely overwrite any contents of the file output.txt if it exists. If the file does not exist, it will be created with the contents "this is a test."

This usage:

$ echo "this is a test" >> output.txt

Will add the link "this is a test" to any content in output.txt (called 'appending'). If the file does not exist, it will be created, and the text will be added.

Answer 6

adding more knowledge here. 

we can also use tee command to perform the same

cat newfile | tee filename - rewrites/replaces the file with new content in filename
cat newfile | tee -a filename - appends to the existing content of the file in filename file