executing history command as another user

Question

I am confused as to why I'm having problems executing a history command as another user to return all that user's history - I need to loop though all users and get their history

cat /etc/passwd | awk -F: '{print $1}' > ${system}.users.txt
while read username; do
   echo $username
      sudo -u $username bash -c 'export HISTTIMEFORMAT="%F %T "; history' >../log/${username}.hist
      #sudo -u $username bash -c 'export HISTTIMEFORMAT="%F %T "; history'
done < ./${system}.users.txt

I get no history output when I run: sudo -u anotheruser history

to troubleshoot I tried: sudo -u anotheruser bash -c 'which history'

Also I ran : sudo find / -name 'history' -type f

and I get no returned executable.

Can anybody tell me why a sudo command can't be executed by another user?

Answer 1

(1) history is a shell builtin; there is no executable

(2) bash -c makes bash noninteractive, and noninteractive shells don't use history. This is not very well documented, but I need both -i and set -o history to get history into a shell with -c:

bash -ic 'set -o history; history'

(Tested in 4.1.2(1) on RedHat and 4.3.11(1) on Ubuntu)

(3) timestamps aren't written to the history file by default, so unless you've (previously) set/forced HISTTIMEFORMAT for your users or they have (previously) deliberately set it, lines/entries read from the history file will (all) have the current time

(4) sudo changes the userid and groupid but not the rest of the environment, so your command will look for the history file of the user running it, not the one in $username; add -i

(5) It might be easier to just read $5/.bash_history -- at least for userids that run bash and have a home directory, which system userids mostly won't