How to concatenate string variables in Bash

Question

In PHP, strings are concatenated together as follows:

$foo = \"Hello\";
$foo .= \" World\";

Here, $foo becomes \"Hello World\"

Answer 1

I don't know about PHP yet, but this works in Linux Bash. If you don't want to affect it to a variable, you could try this:

read pp;  *# Assumes I will affect Hello to pp*
pp=$( printf $pp ;printf ' World'; printf '!');
echo $pp;

>Hello World!

You could place another variable instead of 'Hello' or '!'. You could concatenate more strings as well.

Answer 2

I kind of like making a quick function.

#! /bin/sh -f
function combo() {
    echo $@
}

echo $(combo 'foo''bar')

Yet another way to skin a cat. This time with functions :D

Answer 3

If what you are trying to do is to split a string into several lines, you can use a backslash:

$ a="hello\
> world"
$ echo $a
helloworld

With one space in between:

$ a="hello \
> world"
$ echo $a
hello world

This one also adds only one space in between:

$ a="hello \
>      world"
$ echo $a
hello world

Answer 4

foo="Hello "
foo="$foo World"

     

Answer 5

The way I'd solve the problem is just

$a$b

For example,

a="Hello"
b=" World"
c=$a$b
echo "$c"

which produces

Hello World

If you try to concatenate a string with another string, for example,

a="Hello"
c="$a World"

then echo "$c" will produce

Hello World

with an extra space.

$aWorld

doesn't work, as you may imagine, but

${a}World

produces

HelloWorld

Answer 6

Here is the one through AWK:

$ foo="Hello"
$ foo=$(awk -v var=$foo 'BEGIN{print var" World"}')
$ echo $foo
Hello World