How to combine environment variables and bracket expansion in strings in Linux Bash?

Question

I'd like to write a bash script that would create a directory structure like this:

foo
 | - innerdir1
 | - innerfile1

This action should be repeated multiple times for different directory foo names. Each foo name consists of two parts. So I guess I first need to set environment variables:

    $BAR=something
    $BAZ=anotherthing

And then I need to use them in a script that would produce the mentioned structure with foo's name like $BAR.$BAZ, i.e. something.anotherthing. How do I write such a script?

Answer 1

for BAR in abc def
do
    for BAZ in ghi jkl mno
    do
        mkdir -p "$BAR.$BAZ/innerdir1"
        touch "$BAR.$BAZ/innerfile1"
    done
done

will create:

abc.ghi
 | - innerdir1
 | - innerfile1
abc.jkl
 | - innerdir1
 | - innerfile1
abc.mno
 | - innerdir1
 | - innerfile1
def.ghi
 | - innerdir1
 | - innerfile1
def.jkl
 | - innerdir1
 | - innerfile1
def.mno
 | - innerdir1
 | - innerfile1

Answer 2

Instead of environment variables, pass your names as arguments and write the script to use these arguments -- that would make a more flexible tool.

Lookup 'getopts' at this bash-guide page and other places.

Answer 3

The script:

#!/bin/bash
if [ -z "$BAR" -o -z "$BAZ" ]; then
  echo "This script needs environment variables $BAR and $BAZ to be set."
  exit 1 
fi

dir=$BAR.$BAZ
mkdir $dir
mkdir $dir/innerdir1
touch $dir/innerfile1

Invoke as:

BAR=bar BAZ=baz ./script.sh

This will create: bar.baz/innerdir1 and bar.baz/innerfile1.

Answer 4

You should have a look on

http://tldp.org/LDP/abs/html/arrays.html

A simple start would be:

#!/bin/bash

# define foo array
FOOLIST=()

# can be repeated

# create foonames
BAR="something"
BAZ="anotherthing"

# add to foolist
FOOLIST+=("${BAR}.${BAZ}")

BAR="somethingnew"
FOOLIST+=("2${BAR}.${BAZ}")

BAR="somethingnewer"
FOOLIST+=("3${BAR}.${BAZ}")

# create folders from list
for folder in ${FOOLIST[@]}
do
        mkdir $folder
        mkdir $folder/innerdir1
        mkdir $folder/innerfile1
done