Create users based on a text file using Bash script?

Question

So, I have a text file that is organized like this

<username>:<fullname>:<usergroups>

I need to create a new user for each line and put them into their groups. I am stuck with trying to set username into a variable to use with useradd. I have tried using cut but it needs a file name, I can't just pass it a line.

Here is what I currently have:

#! /bin/bash
linesNum=1 
while read line
do
  echo
  name=$( cut -d ":" -f1 $( line ) )
  ((lineNum+=1))
done < "users.txt"

Thanks for your help!

$(line) is really wrong, it will consider line as a command, what you want is rather "$line" or "${line}". — Benoit
– Benoit, Commented Nov 5, 2010 at 9:18

ocodo · Accepted Answer · 2010-11-05 05:05:52Z

3

#!/bin/bash
while IFS=: read username fullname usergroups
do
    useradd -G $usergroups -c "$fullname" $username
done < users.txt

fullname is the only string that should contains whitespace (hence the quotes), A list of usergroups should be separated from the next by a comma, with no intervening whitespace (so no quotes on that argument) and your username should not contain whitespace either.

Upate:

To get the list of usergroups to create first you can do this...

#!/bin/bash
while IFS=: read username fullname usergroups
do
    echo $usergroups >> allgrouplist.txt
done < users.txt

while IFS=, read group
do
   echo $group >> groups.txt
done < allgrouplist.txt

sort -u groups.txt | while read group
do
   groupadd $group
done

This is a bit long winded, and could be compacted to avoid the use of the additional files allgrouplist.txt and groups.txt but I wanted to make this easy to read. For reference here's a more compact version.

sort -u < $(
       echo $(while IFS=: read a b groups; do echo $groups; done < users.txt )
      | while IFS=, read group; do echo $group; done ) 
| while read group
do
       groupadd $group
done

_{(I screwed the compact version up a bit at first, it should be fine now, but please note I haven't tested this!)}

edited Nov 5, 2010 at 5:05

answered Nov 5, 2010 at 4:14

ocodo

30.5k19 gold badges111 silver badges127 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

amazinghorse24 Over a year ago

Is there a way to do this without adding the user groups before hand? Could I loop through usergroups and create each one before I do useradd? Also: What exactly does IFS=: do? Does it set the field seperator to : ?

user166390 Over a year ago

@amazinghorse24 the bash reference explains the special variables :-)

ocodo Over a year ago

IFS is the standard field separator environment var. You could do the group adding as a separate operation yes, use usermod -g $usergroups $username.

Ignacio Vazquez-Abrams Over a year ago

@amazinghorse: $IFS is the input field separator; it's used by the shell to split the input for various things, such as read. You could do a similar thing with the value of $usergroups, except you pass -d ',' to read to split by commas instead of newlines.

ocodo Over a year ago

I'll update the answer to show how you'd add all the usergroups.

|

Ignacio Vazquez-Abrams · Accepted Answer · 2010-11-05 04:12:14Z

1

IFS=: while read username fullname usergroups
do
  useradd -G "$usergroups" -c "$fullname" "$username"
done < users.txt

answered Nov 5, 2010 at 4:12

Ignacio Vazquez-Abrams

804k160 gold badges1.4k silver badges1.4k bronze badges

Collectives™ on Stack Overflow

Create users based on a text file using Bash script?

2 Answers 2

Upate:

6 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Upate:

6 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related