read: read [-ers] [-a array] [-d delim] [-i text] [-n nchars] [-p prompt] [-t timeout] [-u fd] [name ...]
Read a line from the standard input and split it into fields.
Reads a single line from the standard input, or from file descriptor FD if the -u option is supplied. The line is split into fields as with word splitting, and the first word is assigned to the first NAME, the second word to the second NAME, and so on, with any leftover words assigned to the last NAME. Only the characters found in $IFS are recognized as word delimiters.
If no NAMEs are supplied, the line read is stored in the REPLY variable.
variable ARRAY, starting at zero -d delim continue until the first character of DELIM is read, rather
than newline -e use Readline to obtain the line in an interactive shell -i text Use TEXT as the initial text for Readline -n nchars return after reading NCHARS characters rather than waiting
for a newline -p prompt output the string PROMPT without a trailing newline before
attempting to read -r do not allow backslashes to escape any characters -s do not echo input coming from a terminal -t timeout time out and return failure if a complete line of input is
not read withint TIMEOUT seconds. The value of the TMOUT variable is the default timeout. TIMEOUT may be a fractional number. If TIMEOUT is 0, read returns success only if input is available on the specified file descriptor. The exit status is greater than 128 if the timeout is exceeded -u fd read from file descriptor FD instead of the standard input
Exit Status:
The return code is zero, unless end-of-file is encountered, read times out,
or an invalid file descriptor is supplied as the argument to -u.
readarray: readarray [-n count] [-O origin] [-s count] [-t] [-u fd] [-C callback] [-c quantum] [array]
Read lines from a file into an array variable.
A synonym for `mapfile'.
readonly: readonly [-af] [name[=value] ...] or readonly -p
Mark shell variables as unchangeable.
Mark each NAME as read-only; the values of these NAMEs may not be changed by subsequent assignment. If VALUE is supplied, assign VALUE before marking as read-only.
An argument of `--' disables further option processing.
Exit Status:
Returns success unless an invalid option is given or NAME is invalid.