Bash Idioms

Small, unrelated bash one-liners and patterns worth remembering.

Iterate Over a File

while read -r item
do
        echo "$item"   # use "$item" here
done < "$inFile"

Check If a File Is Sorted and Deduplicated

LC_ALL=C sort filename.txt | uniq -d

If this prints nothing, the file is already sorted and has no duplicates.

Random String Generator

Useful for temp filenames.

randomString () {
        tr -dc "a-zA-Z0-9" < /dev/urandom | fold -w 15 | head -1
}

ANSI Colors for Output

GREEN='\033[0;32m'
RED='\033[0;31m'
YELLOW='\033[1;33m'
NC='\033[0m' # No Color

Check If a Folder Exists

if [[ -d "/path/to/folder" ]]; then
    echo "Folder exists"
fi

if [ ! -d "/path/to/folder" ]; then
    echo "Folder does not exist"
else
    echo "Folder exists"
fi