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How to write bash script for creating user on multiple Linux hosts?


 
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Top Forums Shell Programming and Scripting How to write bash script for creating user on multiple Linux hosts?
# 1  
Old 02-18-2013
Wrench How to write bash script for creating user on multiple Linux hosts?

I wonder whether someone can help me with what I'm trying to achieve

Basically, the objective is one script to create new user on more than 70 linux hosts if required.

Everything works apart from the highlighted part. It gave me an output
passwd: Unknown user name ''. when try to set remote password for new user. It seems like it's trying to set password locally and not remotely.

The idea is all information about username,password,uid,comments is pull out from the file IDENTIFY. That way, if we create new user, people only edit the file than the script.
All fields in the IDENTIFY file separates by white space.

Please help how can I achieve this


Code:
#!/bin/bash

HOSTS="/tmp/test/serverlist"
DDID="IDENTIFY"
HOMEPATH="/home/$UNAME"

for i in `cat $HOSTS` ;
do


UNIQUE=`awk -F " " '{print $1 }' $DDID`

RUID=`ssh $i 'grep "$UNIQUE" /etc/passwd'`

if [[ -ne "$RUID" ]]
        then
                echo "User ID is currently available on $i, ready to add new user"
                UNAME=`awk -F " " '{print $2 }' $DDID`
                PASSWORD=`awk -F " " '{print $3 }' $DDID`
                ROLE=`awk -F " " '{print $4 }' $DDID`

               
                `ssh $i useradd -u "$UNIQUE" -d "$HOMEPATH" -s /bin/bash -c "$ROLE" -m -k /etc/skel/ "$UNAME"`
                `ssh $i echo "$PASSWORD" | passwd --stdin "$UNAME"`

else
                echo "User ID exist on $i, check new ID"

fi
done

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Last edited by radoulov; 02-18-2013 at 06:30 AM.. Reason: Miss highlight fault line
# 2  
Old 02-18-2013
I would do one ssh per host and ship the scripting to the remote host, for speed and simplicity.

For getting hosts from your config file, just:
Code:
while read i
 do
  ...
 done < file

For good error handling, echo each host, time and user as you start each, into a log. you can display the log to the terminal, too, with 'tee -a' or 'tail -f log_file &' (just remember to kill $!). Screens can go poof, and you should keep a report.

A user name can be a substring of any field (like roo or oot !), so put some boundaries in the grep:
Code:
grep -c "^${UNIQUE}:" /etc/passwd

Count 0/1 is a nicer test.
This User Gave Thanks to DGPickett For This Post:
# 3  
Old 02-18-2013
How to write bash script for creating user on multiple Linux hosts?

Thanks DGPickett

I am new in bash, and I didn't totally understand what you're trying to say.

Do you mean, change the for loop to while loop, scp the script to the remote server and run it?

If so, can you shed some light of how while loop fit in my script. I just need some directions that's all

Substring is something that is new to me and will look into it
# 4  
Old 02-18-2013
You can put a whole script on the command line, or just send it into ssh bash. I prefer "echo '...'|ssh ...." but "<<!" is pretty popular, too, just be careful to escape meta like $ from local expansion. No need to leave files lying around or have multiple scripts. Don't forget to set up env on remote shell, like '. ./.profile' or the like.
This User Gave Thanks to DGPickett For This Post:
# 5  
Old 02-18-2013
You should take a look at this thread:

https://www.unix.com/shell-programmin...-remotely.html

In which I propose using the -p parameter of useradd to create the user and assign the password all in one go
This User Gave Thanks to Chubler_XL For This Post:
# 6  
Old 02-18-2013
Passwords should be random and expired already.
This User Gave Thanks to DGPickett For This Post:
# 7  
Old 02-18-2013
Your problem is that the right side of the pipe is executed on the calling host.
You need to force it to the remote host, by quoting:
Code:
ssh $i echo "$PASSWORD" "|" passwd --stdin "$UNAME"

or simpler
Code:
ssh $i echo "$PASSWORD | passwd --stdin $UNAME"

Please omit the backticks! They will run the output as commands. If the output would be "reboot" ... guess what happens!
Further, you can combine two adjacent ssh statements in one ssh statement:
Code:
ssh $i "
useradd -u $UNIQUE -d $HOMEPATH -s /bin/bash -c '$ROLE' -m -k /etc/skel/ $UNAME
echo "$PASSWORD | passwd --stdin $UNAME
"

The calling host sees one multi-line "string".
Within the "" quotes it replaces each $VAR by its value.
$ROLE should be quoted on the remote host; you need either \"$ROLE\" or '$ROLE'. The '' ticks do not replace $ROLE by its value, but this is meaningless on the remote host, because it is already replaced by the calling host. And the calling host treats a ' tick as simple characters if it appears within a "string".
There are many more possible optimizations; DGPicket pointed out some...

Last edited by MadeInGermany; 02-18-2013 at 06:23 PM..
This User Gave Thanks to MadeInGermany For This Post:

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