Linux current user name

How to know your current user in Linux without ‘whoami’ [closed]

Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.

This question does not appear to be about a specific programming problem, a software algorithm, or software tools primarily used by programmers. If you believe the question would be on-topic on another Stack Exchange site, you can leave a comment to explain where the question may be able to be answered.

just wondering, if there is a way to know which user i’m using in linux, without using ‘whoami’ command in terminal. May be there is a way to know it from a file? Some file where the current username is stored or something? Thanks in Advance!

That assumes you’re using that as your user database and not LDAP. That’s not always a safe assumption.

3 Answers 3

The id command can display user information, but when called without arguments it also includes all your groups, so you’ll have to massage the output a bit.

id uid=501(robert) gid=20(staff) groups=20(staff),12(everyone). 

First, use cut to pick up only the user ID part:

id | cut -d " " -f 1 uid=501(robert) 

Then send that through another cut to remove the leading uid= part:

id | cut -d " " -f 1 | cut -c 5- 501(robert) 

Finally, use sed to remove all characters that are not letters:

id | cut -d " " -f 1 | cut -c 5- | sed -E 's/[^a-zA-Z]*//'g robert 

The quick route, as user2394284 mentioned:

Guess I should actually read the man pages I link to.

environment variables USER and/or LOGNAME are usually set up for your convenience.

$ echo $USER bineinfachvorbeigekommen $ echo $LOGNAME bineinfachvorbeigekommen 

On Linux, you can’t be certain that a process is associated with a user name. The best you can be sure of is that it has a numerical user ID. In fact, it will have two numeric user IDs — the «real user ID» and the «effective user ID». Normally these are the same.

These user IDs are exposed by the kernel — there is a kernel system call that retrieves them, and wrappers for that system call in most programming languages (e.g., getuid() in C).

User name, however, is not an intrinsic property of the process, and there’s no knock-down certain way to find it from within an application. In fact, it’s possible to run a process under a (numerical) user ID that has no corresponding name — this is something that won’t normally happen in desktop Linux, but is relatively normal in embedded and container systems.

User names are stored in some authentication database, like /etc/passwd , and can be determined from the user ID — usually. Most Linux shells set environment variables like $LOGNAME and $USER to make life a bit easier for programmers. Utilities like whoami will use various methods to map the numeric user ID to a name, but this won’t be foolproof, for reasons explained above.

Источник

5 Methods to Get Current User Name in Linux/Unix Shell Script

Learn how to retrieve the current user name in a Linux/Unix shell script with 5 different methods. Get key points, important points, and helpful points to ensure a thorough understanding of shell get user name bash.

• Using $USER or $USERNAME Variables
• Checking Current Shell Name
• Obtaining Username from UID Using Cut Command
• Using Whoami and Logname Commands
• Displaying User Information Using ID Command
• Other code samples for retrieving current user name in a Linux/Unix shell script
• Conclusion
• How to get username in shell script?
• How do I get filename in bash?
• How to get user name in Linux?
• How to print current user in Linux?

As a Linux/Unix shell script developer, it’s important to know how to retrieve the current user name in your scripts. There are several methods to accomplish this, and in this blog post, we will explore five of them. By the end of this article, you should be able to confidently retrieve the current user name in your Linux/Unix shell scripts.

Using $USER or $USERNAME Variables

The $USER and $USERNAME variables are widely used in Linux/Unix systems and store the name of the current user account. To display the current user account in your shell script, simply use “echo $USER” or “echo $USERNAME”. However, it’s important to note that the value of these variables should not be used for security decisions. For example, if your script is checking if the current user has permission to access a file, relying solely on the $USER or $USERNAME variable is not secure.

Checking Current Shell Name

Another method to get the current user name in a Linux/Unix shell script is to display the current shell name. You can do this using the command “ps -p $$”, which will display the current shell name. Alternatively, you can print the shell for the current user by using “echo $SHELL” in your shell script.

Obtaining Username from UID Using Cut Command

The UID, or User ID, is a unique identifier assigned to each user account in Linux/Unix systems. In order to retrieve the username from the UID, you can use the “cut” command. The command “getent passwd $UID | cut -d: -f1” will display the username for the specified UID.

Using Whoami and Logname Commands

The “whoami” command prints the effective username of the current user, while the “logname” command prints the user’s login name. An example script using the “logname” command is “by_logname”. You can use these commands in your shell script to retrieve the current user name.

Displaying User Information Using ID Command

The “id” command prints user and group information for the specified user. To display the current user’s information, use “id -un” in your shell script. Additionally, the “id -u” command can be used to display the UID of the current user.

Other code samples for retrieving current user name in a Linux/Unix shell script

In Shell , for instance, bash get username code example

whoami cd /home/USERNAME/Desktop

Conclusion

In this blog post, we have explored several methods to get the current user name in a Linux/Unix shell script. We covered key points such as using $USER or $USERNAME variables, checking the current shell name, and obtaining the username from the UID using the cut command . We also highlighted important points such as the fact that the value of $USER or $USERNAME should not be used for security decisions and that the /etc/passwd file stores user information, including the username. Finally, we provided helpful points such as using the “who” command to display information about users currently logged in and the “id” command to print the UID, GID, and groups of a specified user.

It’s important to choose the method that best suits your needs, depending on the situation and the purpose of your script. With this knowledge, you should be able to confidently retrieve the current user name in your Linux/Unix shell scripts. Remember to always prioritize security when handling user information.

Источник

How to get the logged in user’s real name in Unix?

I’m looking to find out the logged in user’s real (full name) to avoid having to prompt them for it in an app I’m building. I see the finger command will output a columned list of data that includes this and was wondering if it makes sense to grep through this or is there an easier way? None of the switches for finger that I’ve found output just the real name. Any thoughts would be much appreciated.

Right on Beta, that worked beautifully. Do you think that this is safe if there is more than one logged in user? Specifically does your sed magic above return all real name’s or just the first one it encounters? Thanks!

Or: finger blah | grep Name | awk -F «Name:» ‘‘ These will work fine if there are multiple users. It just pulls the one specified.

7 Answers 7

getent passwd `whoami` | cut -d : -f 5 

( getent is usually preferable to grepping /etc/passwd ).

getent passwd "$USER" | cut -d: -f5 | cut -d, -f1 

This first fetches the current user’s line from the passwd database (which might also be stored on NIS or LDAP)

In the fetched line, fields are separated by : delimiters. The GECOS entry is the 5th field, thus the first cut extracts that.

The GECOS entry itself is possibly composed of multiple items — separated by , — of which the full name is the first item. That’s what the second cut extracts. This also works if the GECOS entry is lacking the commas. In that case the whole entry is the first item.

You can also assign the result to a variable:

fullname=$( getent passwd "$USER" | cut -d: -f5 | cut -d, -f1 ) 

Or process it further directly:

echo "$( getent passwd "$USER" | cut -d: -f5 | cut -d, -f1 )'s home is $HOME." 

Источник

How can I find out my user name ( system login username in ubuntu 20.04 )? [closed]

Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.

This question does not appear to be about a specific programming problem, a software algorithm, or software tools primarily used by programmers. If you believe the question would be on-topic on another Stack Exchange site, you can leave a comment to explain where the question may be able to be answered.

How do i find my system login username in Ubuntu 20.04.3 LTS ?

Just type in whoami at the command line. Or if you need it in a script variable, try something like user=$(whoami) (then echo $user or whatever).

1 Answer 1

Use this solution if you didn’t encrypt your home directory.

Do you still have the installation media(LiveCD/USB) from which you installed Ubuntu? Boot from it and select Try Ubuntu.

Go to Files and then, you will see you already installed Ubuntu partition. Click on it, it will mount.

Go to /home. Here you will see a list of all users on the system that you have created.

To jog your memory, however, what is your name? Did you enter the same name while installing Ubuntu? Do you recall the name that was displayed on the login prompt where you entered your password? Ubuntu by default sets the username as your first name in lowercase.

Example; name= John Doe, automatically set username= john

Источник

username Command in Linux With Examples

Linux as an operating system holds the capabilities of handling multiple users. So it is important to keep a check on the users and their related information in order to maintain the integrity and security of the system. Whenever a user is added its information is stored in the “/etc/passwd” file. It keeps the username and other related details. Here are some commands to fetch username and its configurations from the Linux host. There is no specific “username” command in Linux but there are other several sets of commands that let the user access the various users on the machine.

1. id: This command basically prints the information of real and effective user or in other words the current user.

Use the id command followed by the username to print specific user information.

2. getent: This command fetches user information from database configured in /etc/nsswitch.conf. file which also includes passwd database.

Each line above has seven fields separated by colons which contains the following information-

• Username
• Encrypted Password
• User ID number(UID)
• User group ID number(GID)
• Full name of the user(GECOS)
• user home directory and
• Login shell respectively.

Example: Use the finger command followed by the username to print specific user information. Syntax:

Example: 4. lslogins: It displays information about known users in the system. By default, it will list information about all the users in the system.

Example: 5. cat: This command fetches and prints user information from /etc/passwd/ file, where each line contains seven fields as in the output of getent and less command. Syntax:

Example: 6. compgen: This command also displays the name of all the users without any additional information. Syntax:

Example: Note: One can use compgen -c command to list all commands available if he/she is not the admin on a Linux system and doesn’t have the sudo access.

Источник