“>”和“ >>”有什么区别？

Question

What's the difference between

cat int.txt > out.txt

and

cat int.txt >> out.txt

Does the >> do anything differently from > ?

Answer 1

The > will overwrite out.txt if it already exists. The >> will simply append to out.txt .

Answer 2

> overwrites to the file. >> appends to the file.

Answer 3

>> will append to out.txt if it exists

> will overwrite out.txt if it exists

Answer 4

> is to re-direct standard output to the file and overwrite it if the file exists.

>> is to append standard output to the file if it exists

Some more options:

http://www.mathinfo.u-picardie.fr/asch/f/MeCS/courseware/users/help/general/unix/redirection.html

Answer 5

cat int.txt > out.txt

This has written the contents of int.txt to out.txt and overwritten anything that was in that file (out.txt) if it already existed.

cat int.txt >> out.txt

This has appended int.txt to the end of out.txt if it existed or simply created it if it didn't, and copied int.txt into it.