Bash Arrays Cheat Sheet

README.md

Bash Arrays

Declaration

📁 Array

#optional
declare -a array

🗂️ Associative Array

#mandatory
declare -A assocArray

Important

Note the distinction between "-a" for array and "-A" for Associative arrays

Affectation

Whole

📁 Array

array=(elem1 elem2 elem3)

🗂️ Associative Array

assocArray=([key1]=value1 [key2]=value2 [key3]=value3)

Tip

Don't hesitate to make use of "double quotes" if you need trickier values or keys

Push

Note

The syntax is very similar to whole array affectation

📁 Array

array+=elemN

🗂️ Associative Array

assocArray+=([key1]=value1)

Concatenation

Note

You may have noticed but Pushing is basically a concatenation of a 1-sized array for both types

📁 Array

array+=(elemN, elemM, elemO)

🗂️ Associative Array

assocArray+=([key1]=value1 [key2]=value2 [key3]=value3)

Targeted

📁 Array

array[0]=newElem1

Tip

You may set values for arbitrary indexes like just for array[13] & array[12] if you please

🗂️ Associative Array

assocArray[keyX]=valueX

Reading

Values

Individually

📁 Array

echo ${array[0]}

🗂️ Associative Array

echo ${assocArray[keyX]}

Altogether

Clean Mode

📁 Array

echo "${array[@]}"

🗂️ Associative Array

echo "${assocArray[@]}"

Gerbouli (🤮) Mode

📁 Array

echo "${array[*]}"

🗂️ Associative Array

echo "${assocArray[*]}"

Indexes

echo "${!array[@]}"

🗂️ Associative Array

echo "${!assocArray[@]}"

Note

For either type of (Associative) Array the use of ${!array[@]} is equivalent to ${!array[*]} so have fun

Length

📁 Array || 🗂️ Associative Array

echo ${#struct[@]}

Warning

Don't mistake ${#struct[@]} with ${#struct[anIndex]} which would be the size of the value at anIndex in your struct

🛣️ RoadMap (no estimate)

• Present this whole mess is a side by side array fashion
  • (which would be way nicer than currently considering how ironic this is that it is about arrays but is not presented in a very visually structured manner)