Configuration:
OS: Fedora 11 - with all updates applied
Bash: version 4.0.23(1)-release
Problem description:
When stdin is a pipeline to 'mapfile', 'readarray', and 'read -a' shell
built-in commands, they fail to assign any values to the target array.
The array is neither unset nor altered in any way. No error message is
produced, and $? == 0.
None of the available options have any effect on this behavior.
Oddly, when input is provided via keyboard or redirection (<), these
commands function properly. This last point seems really weird to me and
points to the built-ins' or shell's internal handling of a pipeline.
mapfile/readarray example (mapfile behaves identically to readarray):
$ ls -a | readarray # using the default MAPFILE array
$ echo $?
0
$ echo "${#mapfi...@]}"
0
$
Other forms of mapfile/readarray that fail:
$ ls -a | readarray -u0 # specified input file descriptor
$ echo "${#mapfi...@]}"
0
$
$ declare -a myArray # (optional) Declaring myArray has no
effect
$ ls -a | readarray myArray
$ echo "${#myarr...@]}"
0
$
read -a example:
$ ls -a | read -a myArray
$ echo "${#myarr...@]}"
0
$
The other ways of using stdin (i.e. keyboard, file redirection) work
fine. For example:
mapfile/readarray keyboard:
$ readarray myArray # input from keyboard
1
line 2
3
[cntl-D]
$ echo "${#myarr...@]}"
3
$
mapfile/readarray redirection:
$ ls -a > foo
$ readarray myArray < foo
$ echo "${#myarr...@]}"
6
$
read -a redirection:
$ ls -a > foo
$ read -a myArray < foo
$ echo "${#myarr...@]}"
1
$
Rob Robason
r...@robason.net
925-825-1512
