bash - How to apply shell command to each line of a command output?

Question

Suppose I have some output from a command (such as ls -1):

a
b
c
d
e
...

I want to apply a command (say echo) to each one, in turn. E.g.

echo a
echo b
echo c
echo d
echo e
...

What's the easiest way to do that in bash?

Answer 1

It's probably easiest to use xargs. In your case:

ls -1 | xargs -L1 echo

The -L flag ensures the input is read properly. From the man page of xargs:

-L number
    Call utility for every number non-empty lines read. 
    A line ending with a space continues to the next non-empty line. [...]