Get current users username in bash?

Question

I am writing a program in bash that needs to get the user's username.

I have heard of a thing called whoami but I have no idea what it does or how to use it.

What command do I use to get the current username?

Answer 1

On the command line enter

echo "$USER"

or

whoami

To save these values to a variable, do

myvariable=$(whoami)

or

myvariable=$USER

OF course, you don't need to make a variable since that is what the $USER variable is for.

Answer 2

alternative to whoami is id -u -n.

id -u will return the user id (e.g. 0 for root).

Answer 3

A hack the I've used on Solaris 9 and Linux and which works fine for both of them:

ps -o user= -p $$ | awk '{print $1}'

This snippet prints name of user with current EUID.

NOTE: you need bash as interpreter here.

On Solaris you have problems with methods, described above:

• id does not accept -u and -n parameters (so you will have to parse output)
• whoami does not exist (by default)
• who am I prints owner of current terminal (ignores EUID)
• $USER variable is set correctly only after reading profile files (e.g. /etc/profile)

Answer 4

Use the standard Unix/Linux/BSD/MacOS command logname to retrieve the logged in user. This ignores the environment as well as sudo, as these are unreliable reporters. It will always print the logged in user's name and then exit. This command has been around since about 1981.

My-Mac:~ devin$ logname
devin
My-Mac:~ devin$ sudo logname
Password:
devin
My-Mac:~ devin$ sudo su -
My-Mac:~ root# logname
devin
My-Mac:~ root# echo $USER
root

Answer 5

Two commands:

1. id prints the user id along with the groups. Format: uid=usernumber(username) ...

2. whoami gives the current user name

Answer 6

When root (sudo) permissions are required, which is usually 90%+ when using scripts, the above methods always give you root as the answer.

To get the current "logged in" user is just as simple, but requires accessing different variables: $SUDO_UID and $SUDO_USER.

They can be echoed:

echo $SUDO_UID
echo $SUDO_USER

or assigned, e.g.:

myuid=$SUDO_UID
myuname=$SUDO_USER

Answer 7

For bash/ksh/sh etc. Many of your questions are quickly answered by either:

man [function]

to get the documentation for the system you are using.

or usually more conveniently: google "man function" This may give different results for some things where linux and unix have modest differences.

For this question, just enter "whoami" in your shell.

To script it:

myvar=$(whoami)

Answer 8

In Solaris OS- I used this command.

$ who am i     # remember to use it with space.

On Linux- Someone already answered this in comments.

$ whoami       # without space

Answer 9

On Most Linux systems, simply typing whoami on the command line provides the user ID.

However, on Solaris, you may have to determine the user ID, by determining the UID of the user logged-in through the command below.

echo $UID

Once the UID is known, find the user by matching the UID against the /etc/passwd.

cat /etc/passwd | cut -d":" -f1,3

Answer 10

The current user's username can be gotten in pure Bash with the ${parameter@operator} parameter expansion (introduced in Bash 4.4):

$ : \\u
$ printf '%s\n' "${_@P}"

The : built-in (synonym of true) is used instead of a temporary variable by setting the last argument, which is stored in $_. We then expand it (\u) as if it were a prompt string with the P operator.

This is better than using $USER, as $USER is just a regular environmental variable; it can be modified, unset, etc. Even if it isn't intentionally tampered with, a common case where it's still incorrect is when the user is switched without starting a login shell (su's default).

Answer 11

Get the current task's user_struct

#define get_current_user()              \
({                                      \
    struct user_struct *__u;            \
    const struct cred *__cred;          \
    __cred = current_cred();            \
    __u = get_uid(__cred->user);        \
    __u;                                \
})