[colug-432] Argument Quoting in BASH

[jep200404 at columbus.rr.com]

On Wed, 15 Apr 2015 09:51:48 -0400, zach villers <zachvatwork at gmail.com> wrote:

> Is there a difference between;
> 
> ls -l | grep ^...s
> 
> AND
> 
> ls -l | grep "^...s"
> 
> *trying to find files with setuid permission*
> 
> A trainer told me using quotes with the grep statement was necessary,
> but it doesn't seem to be.

That depends on what is inside the quotes.
There is no difference in this case 
with the bash shell that I'm using. 

    show[zach at colug ~]$ showargs ^...s
    There are 1 arguments
    /home/jep/bin/showargs '^...s'
    [zach at colug ~]$ showargs "^...s"
    There are 1 arguments
    /home/jep/bin/showargs '^...s'
    [zach at colug ~]$ cat ~/bin/showargs
    echo "There are $# arguments"
    echo -n "$0"
    i=1
    while [ $# -ne 0 ] ; do
       echo -n " '$1'"
       i=`expr $i + 1`
       shift
    done
    echo
    [zach at colug ~]$ 

Study difference between using no quotes, single quotes, 
double quotes, and graves (aka "back ticks"). 
It is important to understand those differences. 

    [zach at colug ~]$ f='hello world'
    [zach at colug ~]$ showargs echo spam $f eggs
    There are 5 arguments
    /home/jep/bin/showargs 'echo' 'spam' 'hello' 'world' 'eggs'
    [zach at colug ~]$ showargs "echo spam $f eggs"
    There are 1 arguments
    /home/jep/bin/showargs 'echo spam hello world eggs'
    [zach at colug ~]$ showargs 'echo spam $f eggs'
    There are 1 arguments
    /home/jep/bin/showargs 'echo spam $f eggs'
    [zach at colug ~]$ showargs `echo spam $f eggs`
    There are 4 arguments
    /home/jep/bin/showargs 'spam' 'hello' 'world' 'eggs'
    [zach at colug ~]$ 

By the way, I usually enclose my regular expression for grep 
and commands for sed with single quotes, not double quotes.