Suppress output of ftp in a shell script while executed in a cron job

Question

I'm running a backup shell script every night where i tar some data and then send it to a different server by sftp. As this is really important data i would like to get noticed by email if something goes wrong. Thats why i opted in to get notified if errors occur in the cron job (managed server).

This is how the sftp connection looks like:

sftp -i ~/.ssh/id_rsa server.com <<EOF
put $file
rm $file_old
EOF

Unfortunately right now i get a mail every time the script runs showing me the output of the sftp connection like this:

Connected to server.com.
% Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                               Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0

The script works and the files are transferred. So is there a way to hide the output of the sftp connection but yet show possible errors of the script. Any help is greatly appreciated!

Answer 1

The samples way to suppress those progress bars is to exec command as follow:

sftp -q -i ~/.ssh/id_rsa server.com <<EOF
put $file
rm $file_old
EOF

And this command will display errors on STDERR

Answer 2

You can redirect the output of the sftp:

sftp -i ~/.ssh/id_rsa server.com > /dev/null 2>&1 <<EOF

This way you will not see the output.

Then, if you want to see the possible errors, you can use:

sftp -i ~/.ssh/id_rsa server.com > /dev/null 2>&1 <<EOF
put $file
rm $file_old
EOF
sftp_status=$?
case $sftp_status in
    0) sftp_error="";;
    1) sftp_error="Error 1: Generic error - Undetermined error in file copy";;
    2) sftp_error="Error 2: Remote host connection failure";;
    3) sftp_error="Error 3: Destination is not directory, but it should be";;
    4) sftp_error="Error 4: Connecting to host failed";;
    5) sftp_error="Error 5: Connection lost for some reason";;
    6) sftp_error="Error 6: File does not exist";;
    7) sftp_error="Error 7: No permission to access file";;
    8) sftp_error="Error 8: Undetermined error from sshfilexfer";;
    9) sftp_error="Error 9: File transfer protocol mismatch";;
    65) sftp_error="Error 65: Host not allowed to connect";;
    66) sftp_error="Error 66: Protocol error";;
    67) sftp_error="Error 67: Key exchange failed";;
    68) sftp_error="Error 68: Host authentication failed";;
    69) sftp_error="Error 69: MAC error";;
    70) sftp_error="Error 70: Compression error (not used in SSH2)";;
    71) sftp_error="Error 71: Service not available";;
    72) sftp_error="Error 72: Protocol version not supported";;
    73) sftp_error="Error 73: Host key not verifiable";;
    74) sftp_error="Error 74: Connection lost";;
    75) sftp_error="Error 75: Disconnected by application";;
    76) sftp_error="Error 76: Too many connections";;
    77) sftp_error="Error 77: Cancelled by user";;
    78) sftp_error="Error 78: No more auth methods available";;
    79) sftp_error="Error 79: Illegal user name";;
    255) sftp_error="Error 255: Error occurred in SSH";;
    *) sftp_error="Unknown sftp Error";;
esac
echo $sftp_error

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