Search code examples
bashshelltargnupgtee

creating a tarball, encrypt it on the fly and keeps tar messages in a log file

On OSX I'm trying to create a tarball of a directory and on the fly encrypt it with gpg and keeps the output of the tar messages in a log file for later analysis.

While the tar+gpg on the fly it's pretty easy

tar zcvf - foo | gpg -e -r foo@bar.com -o foo.tgz.gpg

so far I'm failing to log the output of tar (and maybe the gpg one in case) to a log file.

I tried several combination of

tar | gpg | tee
tar | gpg 2>&1 >(tee)
tar | gpg > file.log

any help here?

Cheers Davide

Solution

  • 2> file.log should achieve it. If you want to tee the stderr stream and also keep it going to the original destination, you can achieve that with

    2> >(tee file.log >&2)

    In your example:

    tar zcvf - foo 2> >(tee file.log >&2) | gpg -e -r foo@bar.com -o foo.tgz.gpg

    Your attempts don't succeed because the piping (|) only forwards stdout of the previous command to the stdin of the current one. The current command (gpg) doesn't have access to the stderr of the previous command (tar). That stderr has already gone to its destination (your terminal, most likely).

    2> >(command ) pipes (quite literally >() create an unnamed, OS-level pipe underneath) stderr to stdin of command. Since command is a child process, its stderr (#2) descriptor will point to the same file as the stderr of the parent process.