Add new users from a text file in bash script

问题:

I am new to Scripting, and I am not sure what is wrong with mine. I have not yet added groupadd or useradd commands to actually add the user yet, but I will once I get this part working. So far I have:

!#/bin/bash

if [$# -ne 0 ]
then
    echo "usage: $0 < file'
    exit 1
fi

first=cut -f 1 -d ',' user_list
last=cut -f 2 -d ',' user_list
lastl=cut -f 2 -d ',' user_list | head -c 1

usern=$first $lastl | tr 'A-Z' 'a-z'
tname=$first $last
while read line; do
    echo "adding $tname : $usern\n"
done < user_text

The output should look like adding Jet Black: jetb but its kind of all over the place. Any help or hints as to what I'm doing wrong would help a lot.

回答1:

You could probably make it a lot simpler by reading up on the role of the IFS variable in word splitting, then writing something like this:

while IFS=, read first last
do
  usern=$(echo "${first}${last:0:1}" | tr [:upper:] [:lower:])
  tname="${first} ${last}"
  echo "adding ${tname} : ${usern}"
done

Some other things in there to research - substring expansion (${last:0:1}), character classes for tr ([:upper:], etc.), capturing output from commands ($(...)).

回答2:

This is a syntactically correct version of your script:

#!/bin/bash

if [ $# -ne 0 ]
then
        echo "usage: $0 < file"
        exit 1
fi

while read user_list
do
        first=`echo $user_list | cut -f 1 -d ','`
        last=`echo $user_list | cut -f 2 -d ','`
        lastl=`echo $last | head -c 1`

        usern=`echo $first $lastl | tr 'A-Z' 'a-z'`
        tname=`echo $first $last`
        echo "adding $tname : $usern\n"
done < user_text

I think you want to delete the space between $first and $lastl in $usern, like this:

usern=`echo ${first}${lastl} | tr 'A-Z' 'a-z'`

And then there are lots of improvements to do, probably like twalberg said, but I think your best first step is to understand your syntax errors.