How to tell the "last" command to read from STDIN?

Question

SERVER:~ # zcat /var/log/wtmp-20130827.gz | last -f -
last: -: No such file or directory
SERVER:~ # 

Without uncompressing the wtmp file, how can I see the output of if it with the last command?

Answer 1

last doesn't support reading from a pipe. You can use /dev/stdin as a file name, but that's kind of useless since it only works if you're redirecting from a file in the first place.

Uncompress the file to a temporary file.

wtmp=$(mktemp)
zcat /var/log/wtmp-20130827.gz >|"$wtmp"
last -f "$wtmp"
rm -f "$wtmp"

Zsh has a form of process substitution =(…) which puts the output of a command in a temporary file.

last -f =(zcat /var/log/wtmp-20130827.gz)

Answer 2

No way.

last(1) is not designed to be able to read stdin. Either /var/log/wtmp or -f xxx

It doesn't support '-'