mapfile
Read lines from stdin into a bash array
TLDR
SYNOPSIS
mapfile [options] [array]
DESCRIPTION
mapfile (also known as readarray) is a bash builtin that reads lines from standard input into an indexed array variable. Without a variable name, it uses the default array `MAPFILE`.
It is significantly faster than a `while read` loop for reading files into arrays, as it is implemented as a builtin rather than running in a subshell.
PARAMETERS
ARRAY
Array variable name.-n COUNT
Maximum lines to read.-s COUNT
Lines to skip.-t
Remove trailing delimiters.-d DELIM
Use delimiter instead of newline (bash 4.4+).-O ORIGIN
Start assigning at array index ORIGIN (default: 0).-C CALLBACK
Call CALLBACK after reading each line.-c QUANTUM
Call CALLBACK every QUANTUM lines (default: 5000).
CAVEATS
Bash-specific builtin (bash 4.0+). Not available in sh or other POSIX shells. The `-d` option requires bash 4.4 or later. Cannot read from a pipe in a subshell context -- use process substitution (`< <(command)`) instead of piping (`command | mapfile`).
HISTORY
mapfile was added to Bash 4.0 (released 2009) as a builtin for efficiently reading files into arrays. The `-d` delimiter option was added in Bash 4.4.
