Creating an array out of users: shell script

UNIX BSD
1

I want to create a shell script for a menu selection consisting of users defined on the machine. To an administrator having the privileges, the selection menu will look as follows:

Select the user you want to define the variables for:
1) my-username-1
2) my-username-2
etc

Then there would be a read statement, such as the following:

read $OPTION

of which #OPTION holds the name of the user for whom the task should be performed.
A start would be to use the following:

cat /etc/passwd | grep home | cut -d : -f 1

How do I turn this into an array or at least something that allows the creation of a selection menu?
Can I reasonably assume that all defined users have a directory in /usr/home?

2

One option:

USERS=("" $(awk -F: '{print $1}' /etc/passwd))

echo ${USERS[@]} | awk '{print ++C ") " $1}' RS=" "

printf "Enter a number:  "
read OPTION

echo You chose ${USERS[$OPTION]}

Or you could use select, for example:

USERS=("" $(awk -F: '{print $1}' /etc/passwd))

PS3="Select a user: "
select USER in ${USERS[@]}; do
 break
done

echo You chose $USER

(you need to modify the awk to remove blank lines, comments and system users)

3

Thank you very much for your response.
In both cases I am getting the following error message:

./test-selection-menu.sh: 1: Syntax error: word unexpected (expecting ")")

The following line:

$(awk -F: '{print $1}' /etc/passwd)

already generates the list of users on its own, so what does the first part of USERS do?

(""

I looked into selection menus a bit more and I see PS3 a lot in discussions about this. Is PS3 a reserved acronym?

4

You don't need the "" with the select version, actually.

It is used in the first version because arrays are zero-based (the first element would be index 0). The "" was to use up element 0, so that the usernames would begin at index 1.

For this problem, I would probably use the select approach.

What shell do you use?

5

Thank you again for your response.
I am using /bin/csh under FreeBSD 8.1 x64.
I have tried many variations of the select script, but I either get an error as such:

${USERSx[...}: Bad substitution

or as such:

Command not found

Could this have to do with the shell?
Also, I am assuming no #!/usr/bin/sh or such directive is needed as the first line?

6

I'd say it has everything to do with the shell. Why are you using that?

You can eliminate the array totally, if using select, but as I don't think csh has a select, that's neither here, nor there!

You should always put "#!/usr/bin/sh or such directive" in the first line. Just preferably not #!/bin/csh!!

7

I am using the csh, because it is part of the standard install of FreeBSD 8.1 x64. This script happens to be tested on a sandbox machine that is reinstalled every few days.
I currently have the following script ("x" appended to be sure that variables do not interfere with reserved words):

#!/usr/bin/sh
USERSx=$(awk -F: '{print $1}' /etc/passwd)
PS3="Select a user: "
select USERx in ${USERSx[@]}; do
 break
done
echo You chose $USERx

This leads to a Command not found error, regardless of whether I use eval, `` quotes, extra parentheses etc.

8

It should also have a bourne shell of some sort installed as standard to be called UNIX at all.

csh programming is strongly recommended against for reasons including, but definitely not limited to these:
Csh Programming Considered Harmful
http://www.grymoire.com/Unix/CshTop10.txt
Csh

...but the most important reason is that programming in CSH is an exercise in masochism. The pituful ad-hoc throws errors that almost never have anything to do with the actual mistake made.