How to send multiple commands to sftp using one line

scriptingsftp

The following command sends one command to sftp using one line:

sftp -o PasswordAuthentication=no user@host" <<<"lcd /home"

How to send multiple lines to sftp using one line. Is there a way to insert carriage returns or something to achieve this, for example:

sftp -o PasswordAuthentication=no user@host" <<<"lcd /home\n cd /myhome\n get file"

The idea is to NOT use the sftp -b option where an external file listing commands is loaded.

Best Answer

From the here-string (<<<) syntax you used I guess your shell is bash, so you can also use string with backslash-escaped characters ($''):

sftp -o PasswordAuthentication=no user@host <<< $'lcd /home\n cd /myhome\n get file'

The portable alternative is here-document:

sftp -o PasswordAuthentication=no user@host <<END
lcd /home
cd /myhome
get file
END

Related Solutions

Sed – How to Remove Multiple Blank Lines from a File

Case 1:

awk '!NF {if (++n <= 2) print; next}; {n=0;print}'

Case 2:

awk '!NF {s = s $0 "\n"; n++; next}
     {if (n>1) printf "%s", s; n=0; s=""; print}
     END {if (n>1) printf "%s", s}'

SFTP – Activity Logging Level in SFTP

Here's some sample log file output:

Feb 26 23:04:55 pegasus internal-sftp[32524]: session opened for local user joeuser from [123.123.123.123]
Feb 26 23:04:57 pegasus internal-sftp[32524]: opendir "/home/joeuser"
Feb 26 23:04:58 pegasus internal-sftp[32524]: closedir "/home/joeuser"
Feb 26 23:05:01 pegasus internal-sftp[32524]: opendir "/home/joeuser/"
Feb 26 23:05:01 pegasus internal-sftp[32524]: closedir "/home/joeuser/"
Feb 26 23:05:02 pegasus internal-sftp[32524]: opendir "/home/joeuser/upload"
Feb 26 23:05:02 pegasus internal-sftp[32524]: closedir "/home/joeuser/upload"
Feb 26 23:05:07 pegasus internal-sftp[32524]: opendir "/home/joeuser/upload"
Feb 26 23:05:07 pegasus internal-sftp[32524]: closedir "/home/joeuser/upload"
Feb 26 23:05:09 pegasus internal-sftp[32524]: session closed for local user joeuser from [123.123.123.123]

Which user is which?

If you take notice of the output above there is a number between square brackets , internal-sftp[32524]. The number is 32524. This represents the session ID for user joeuser, so you can use this string together which messages relate to which user's login.

Rotating the logs

You can modify the log rotation schedule for various logs under /etc/logrotate.d/*. Each log file typically has a corresponding file in this directory. So you could change the syslog file there, for example or create your own for your sftp.log logfile.

Also logrotate has a configuration file, /etc/logrotate.conf which contains these lines:

# rotate log files weekly
weekly

# keep 4 weeks worth of backlogs
rotate 4

These are what the files in the /etc/logrotate.d directory use, if they don't have a setting of their own. So most files are rotated weekly and 4 of them are kept. If you wanted to keep 6 months it would be 4*6 = 24 for the rotate option to keep 6 months, roughly.

Example

Given you're logging to /var/log/sftp.log via syslog you'll need to make your changes in this file, /etc/logrotate.d/syslog. Your file will look like this after making the required changes:

/var/log/cron
/var/log/maillog
/var/log/messages
/var/log/secure
/var/log/spooler
/var/log/sftp.log
{
    rotate 24
    sharedscripts
    postrotate
        /bin/kill -HUP `cat /var/run/syslogd.pid 2> /dev/null` 2> /dev/null || true
    endscript
}

Since you're using syslog you'll have to rotate all these log files as well, keep 24 weeks worth of these as well. If this is unacceptable then your only other course of action would be to create a separate section in this file, syslog like so:

/var/log/cron
/var/log/maillog
/var/log/messages
/var/log/secure
/var/log/spooler
{
    sharedscripts
    postrotate
        /bin/kill -HUP `cat /var/run/syslogd.pid 2> /dev/null` 2> /dev/null || true
    endscript
}

/var/log/sftp.log
{
    rotate 24
    sharedscripts
    postrotate
        /bin/kill -HUP `cat /var/run/syslogd.pid 2> /dev/null` 2> /dev/null || true
    endscript
}

This has some side-effects, one being that you'll be restarting the syslog daemon 2 times each week instead of once. But the logroate syntax does not allow for fine granular control of the rotation schedule for certain logfiles while not rotating others, when the log files are being generated by the same service, i.e. syslog.

References

SFTP file transfer session activity logging