Typing Variables

Declare weakly typed variables

declare is an internal command of bash. (internal command use help for displaying “manpage”). It is used to show and define variables or show function bodies.

Syntax: declare [options] [name[=value]]…

# options are used to define
# an integer
declare -i myInteger
declare -i anotherInt=10
# an array with values
declare -a anArray=( one two three)
# an assoc Array
declare -A assocArray=( [element1]="something" [second]=anotherthing )
# note that bash recognizes the string context within []

# some modifiers exist
# uppercase content
declare -u big='this will be uppercase'
# same for lower case
declare -l small='THIS WILL BE LOWERCASE'

# readonly array
declare -ra constarray=( eternal true and unchangeable )

# export integer to environment
declare -xi importantInt=42

You can use also the + which takes away the given attribute. Mostly useless, just for completness.

To display variables and/or functions there are some options too

# printing definded vars and functions
declare -f
# restrict output to functions only
declare -F # if debugging prints line number and filename defined in too