How can shell scripts check user ID?

just like whoami gives u the user name, i want to know a thinkg which shud tell me
whereami i.e where am i on file system

any 1 help

Um, that'd be one of the most basic Unix commands:

pwd

if you wanted you could also use environment variables to solve both of these problems,

echo $USER - user name
echo $LOGNAME - logname
echo $PWD - print working directory

to view all environment variables type 'printenv' (no quotes)

how can i check if the user exist or not.
note that I can check it in /etc/passwd
but I wanna make it in script to tell me directly if the user exist or not.
same for the group.

thank you.

how can add a new user account in the text mode or terminal

What about using the bash shell's built in $UID variable?

It only prints out a number, but makes for easy checks against root (0).

ggjones1, I don't think that'd be too reliable. What if I ran a script like this:

UID=0 runmyscript.sh

and then had a simple test internally to see if UID was zero?

in fact UID don't become 0 if user use "sudo" instead of become root

Thanks for the information. Was helpful with my script which needs to be executed as root.

Thanks a bunch!!!

Cheers!

How to you do this within a tsch shell?

to get the "real" user (even if you use "su -"), the who command can be used with either the -m flag OR in the form who ARG1 ARG2 ("who am i" or "who yo daddy").

id or $UID will NOT give you this if you use the "-" after the su command :)

the "id" command can give you JUST the current user id (uid) or JUST the current group id (gid) using the -u or -g flags respectively. This is nice for shell scripts like:

--------------------------------------------
if [ `id -u` -ne 0 ]
then
echo "You must be root to execute `basename $0`"
fi