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Top Forums Shell Programming and Scripting Question related to bash. Your help needed.
# 1  
Old 09-15-2016
Question related to bash. Your help needed.
Dear Team,

i have one question related to automation of adding new users based on txt file.

Here we go:

I have data.txt file which shows:

Code:
bang
dang
benc

One by one, after pressing enter. And now, I need scirpt which will add those users with home directory hidden within the file data.txt. I am working on redhat 7.

Code:
!#/bin/bash

for i in 'data.txt'
do
useradd $i -d /home/$i
done
echo Users created.

Could You help?


Moderator's Comments:
Mod Comment Please use CODE tags (for data as well) as required by forum rules!
Last edited by RudiC; 09-15-2016 at 06:42 PM.. Reason: Added CODE tags.
# 2  
Old 09-15-2016
Code tags for code please.

Code:
while read LINE
do
        echo useradd "$LINE" -d /home/$LINE
done < data.txt

Remove the echo once you've tested and are sure it does what you want.
This User Gave Thanks to Corona688 For This Post:
protos27
# 3  
Old 09-15-2016
Something wrong again, could You type full body of this sciprt?

I have to execute this like ./scirpt.sh data.txt right?

Very thank You for your help.
Last edited by rbatte1; 09-16-2016 at 04:19 AM.. Reason: Added ICODE tags for inline code.
# 4  
Old 09-15-2016
Code:
#!/bin/sh

while read LINE
do
        echo useradd "$LINE" -d /home/$LINE
done < data.txt

If that doesn't work please tell me in what way it didn't work, not just that it didn't.
This User Gave Thanks to Corona688 For This Post:
protos27
# 5  
Old 09-15-2016
May i ?
Code:
#!/bin/bash

while read LINE
do
  echo useradd "$LINE" -d /home/$LINE
done < $1

Execute it as
Code:
./script.sh data.txt

This User Gave Thanks to greet_sed For This Post:
protos27
# 6  
Old 09-15-2016
Code:
#!/bin/bash  while read LINE do   
echo useradd "$LINE" -d /home/$LINE
useradd "$LINE" -d /home/$LINE
 done < $1

Will work properly. Thanks, but what when i want to put "load" data from data.txt instad of keyword like LIKE???? I mean for example for $i in "here i will put name of the file etc" is that possible? or similar way like i did it within first post?

When it comes to Corona's version

Code:
while read LINE do         
echo useradd "$LINE" -d /home/$LINE
useradd "$LINE" -d /home/$LINE
 done < data.txt

Also works properly. Thank both of You!
# 7  
Old 09-15-2016
Quote:
Originally Posted by protos27
Thanks, but what when i want to put "load" data from data.txt instad of keyword like LIKE???? I mean for example for $i in "here i will put name of the file etc" is that possible?
What you are asking for is a very persistently repeated beginner shell programming mistake called "Dangerous Backticks".

Quote:
(From the URL above)

A special idiom to pay attention to, because it's basically always wrong, is this:

Code:
    	for f in `cat file`; do
    	    ...
    	done

Apart from the classical Useless Use of Cat here, the backticks are outright dangerous, unless you know the result of the backticks is going to be less than or equal to how long a command line your shell can accept. (Actually, this is a kernel limitation. The constant ARG_MAX in your limits.h should tell you how much your own system can take. POSIX requires ARG_MAX to be at least 4,096 bytes.)
It wastes time, memory, external calls, and subshells to slowly and unreliably almost do what you wanted. The read shell builtin actually reads lines, running externals in backticks do not -- they split on any spaces at all.
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