Bash Cookbook

How to do it...

Let's start our activity as follows:

1. Begin by opening a terminal and a new shell script called bad_input.sh with the following contents:

#!/bin/bashFILE_NAME=$1echo $FILE_NAMEls $FILE_NAME

2. Now, run the following commands:

$ touch TEST.txt$ mkdir new_dir/$ bash bad_input.sh "."$ bash bad_input.sh "../"

3. Create a second script called better_input.sh:

#!/bin/bashFILE_NAME=$1# first, strip underscoresFILE_NAME_CLEAN=${FILE_NAME//_/}FILE_NAME_CLEAN=$(sed 's/..//g' <<< ${FILE_NAME_CLEAN})# next, replace spaces with underscoresFILE_NAME_CLEAN=${FILE_NAME_CLEAN// /_}# now, clean out anything that's not alphanumeric or an underscoreFILE_NAME_CLEAN=${FILE_NAME_CLEAN//[^a-zA-Z0-9_.]/}# here you should check to see if the file exists ...