pulling a column from a file in ksh

Shell Programming and Scripting
1

I would like to pull a column from a file and place it in a variable:

The file would look like this:

N.Korea gibberish garbage
S.Korea gibberish garbage
USA gibberish garbage
Iraq gibberish garbage
Canada gibberish garbage

and items in the first column would be one word only. I would like to place the whole column in a variable. I think sed would be good for this, but I'm not sure of the syntax.
Thanks

2

How about:

x=$(cut -d ' ' -f 1 < file)
3

The file was actually tab-delimited so I ended up using this:

x=$(cut -f1 < file)

which achieved the results I was looking for. Thanks!

4

x=$(cut -d ' ' -f 1 < file)

What shell is syntax from? Is this a form of command grouping used in csh?

or

If this is Korn Shell, why dont you have to use back quotes ( ` ) to execute the commands inside the parens? Are there limitations to this sort of syntax?

5

This is not csh syntax, it is ksh syntax. Note that the title of this thread explicitly mentions ksh. In ksh, the $(command) is preferred, while the `command` syntax is currently supported for backward compatibility.

The advantage is nesting:
gcos=$(grep $(whoami) /etc/passwd | cut -d: -f5)
is easy to code and easy to read. Depending on the contents of the gcos field:
eval gcos=\`grep `whoami` /etc/passwd \| cut -d: -f5 \'
may or may not work.

6

Well, here's where it gets tricky:

It turns out that I do need to use the second column. The file would now look like this:

N.Korea NUCLEAR garbage
S.Korea NON-NUCLEAR garbage
USA NUCLEAR garbage
Iraq UNKNOWN garbage
Canada HORSEBACK garbage

(By the way, the second column is a joke, for those who don't get my sense of humor)

But what I need to do is pull out the second column and place it in a separate variable, but in a way that I can still associate it with the first column.

7

How about:

y=$(cut -f 2 < file)
8

I wanted to be able to still associate column 1 with column 2, so what I ended up doing was:

9

I though that needed entire columns in those variables. You can get individual fields with:

exec < file.txt
while read x y junk ; do
     commands
done