UNIX for Dummies Questions & Answers

Hi I'm here again.

This time I have a question that is not a really issue because I 've already found a workaround but I don't know if the behaviour is correct or not.

In my ksh shell I open a sftp connection to a remote machine.
this is the code:

Code:

sftp ${Csi_USER}@${Csi_HOST}<<EOF0 >> ${FTP_LOG_FILE} 2>> ${FTP_ERR_FILE}

where FTP_LOG_FILE and FTP_ERR_FILE are the files (with the path) for logging.
Meanwhile the FTP_LOG_FILE has always size > 0 I expect the opposite for FTP_ERR_FILE so only if there are errors the file should have size > 0.
Unfortunately this is not true because the FTP_ERR_FILE has always size > 0. It contains n lines one for an open connection like:
Connecting to 10.129.171.80...
Connecting to 10.129.171.80...
Connecting to 10.129.171.80...
Connecting to 10.129.171.80...
Is it possible to avoid this behaviour or it's the standard?
Thanks a lot.

That may be because the sftp command is writing those lines to standard error (file descriptor 2) and not standard output (file descriptor 1). You don't see the difference (probably) while invoking sftp on the command line because for you, both standard error and standard output are the same, that is, the terminal.
Commands do this so that such messages aren't propagated to other commands in a pipeline.