Question

I’m trying to automate a script that copies a file from my local server to a remote server on the command line. I’ve done the research on scp and know how to copy the file to the remote server, but then I want to append that file to another.

This is my code:

scp ~/file.txt user@host:
ssh user@host cat file.txt >> other_file.txt

When I enter everything into the command line manually as such, everything works fine:

scp ~/file.txt user@host:
ssh user@host
cat file.txt >> other_file.txt

But when I run the script, only the file is copied, not appended to the end of other_file.txt. Help?

Answer 1

The second line of your code should be

ssh user@host "cat file.txt >> other_file.txt"

Three important points:

1. You don’t want your local shell to interpret >> in any way (which it does if it’s unquoted)
2. There is a remote shell which will interpret >> in the command correctly.
3. Final arguments to ssh are “joined” to form a command, not carried into an argv array as they are. It may be convenient but it also may lead to confusion or bugs: ssh cat "$MYFILE" and ssh "cat '$MYFILE'" both work in a common use case, but they both break for different values of $MYFILE.