mapfile also called (read array) is a command of the Bash shell used to read arrays. It reads lines from the standard input into an array variable. Also, mapfile must read from substitution (< <) and not from a pipe. Also, mapfile is faster and more convenient when compared to a read loop. It returns 1 or 0 depending on whether the command was successful or not. If no array name is not specified, the default variable MAPFILE is used as the target array variable.
Syntax: mapfile [array]
Alternatively, we can use read array [arrayname] instead of mapfile.
Example 1. Reading an array from a file:
$ mapfile MYFILE < example.txt
$ echo ${MYFILE[@]}
$ echo ${MYFILE[0]}Output:
Example 2. Capture the output into an array:
$ mapfile GEEKSFORGEEKS < <(printf "Item 1\nItem 2\nItem 3\n")
$ echo ${GEEKSFORGEEKS[@]}Here, Item1, Item2, and Item 3 have been stored in the array GEEKSFORGEEKS.
Output:
Example 3. Strip newlines and store item using -t:
$ mapfile -t GEEKSFORGEEKS< <(printf "Item 1\nItem 2\nItem 3\n")
$ printf "%s\n" "${GEEKSFORGEEKS[@]}"Output:
Example 4. Read the specified number of lines using -n:
$ mapfile -n 2 GEEKSFORGEEKS < example.txt
$ echo ${GEEKSFORGEEKS[@]}It reads at most 2 lines. If 0 is specified then all lines are considered.
Output: