SHELL命令之who、whoami、id

root@bt:~/test# who --helpUsage: who [OPTION]... [ FILE | ARG1 ARG2 ]Print information about users who are currently logged in.  -a, --all         same as -b -d --login -p -r -t -T -u  -b, --boot        time of last system boot  -d, --dead        print dead processes  -H, --heading     print line of column headings      --ips         print ips instead of hostnames. with --lookup,                    canonicalizes based on stored IP, if available,                    rather than stored hostname  -l, --login       print system login processes      --lookup      attempt to canonicalize hostnames via DNS  -m                only hostname and user associated with stdin  -p, --process     print active processes spawned by init  -q, --count       all login names and number of users logged on  -r, --runlevel    print current runlevel  -s, --short       print only name, line, and time (default)  -t, --time        print last system clock change  -T, -w, --mesg    add user's message status as +, - or ?  -u, --users       list users logged in      --message     same as -T      --writable    same as -T      --help     display this help and exit      --version  output version information and exit

root@bt:~/test# whoamirootroot@bt:~/test# iduid=0(root) gid=0(root) groups=0(root)root@bt:~/test#