bash: check if remote file exists using scp
I am writing a bash script to copy a file from a remote server, to my local machine. I need to check to see if the file is available, so I can take an alternative action if it is not there.
I know how to test if a local file exists, however, using scp complicates things a bit. Common sense tells me that one way would be to try to scp the file anyhow, and check the return code from the scp command. Is this the correct way to go about it?
If yes, how do I test the return code from the scp invocation?
Answer
using ssh + some shell code embedded in the cmd line; use this method when you need to take a decision before the file transfer will fail;
ssh remote-host 'sh -c "if [ -f ~/myfile ] ; then gzip -c ~/myfile ; fi" ' | gzip -dc > /tmp/pkparse.py
if you want to transfer directories you may want to "tar"-it first
if you want to use scp you can check the return code like this:
if scp remote-host:~/myfile ./ >&/dev/null ; then echo "transfer OK" ; else echo "transfer failed" ; fi
it really depends on when its important for you to know if the file is there or not; before the transfer starts (use ssh+sh) or after its finished.