(I think this is a good problem for Pranav to tackle if you consider this to be a bug, Chet).
Current behavior: dualbus@debian:~$ bash -c 'read -n0 <<< "abc"; declare -p REPLY' declare -- REPLY="abc" dualbus@debian:~$ bash --version|head -n1 GNU bash, version 4.4.11(1)-release (x86_64-pc-linux-gnu) Expected behavior: #1 nchars <= 0 treated as an error i.e. dualbus@debian:~/src/gnu/bash-build$ ./bash -c 'read -n0 <<< "abc"; declare -p REPLY' ./bash: line 0: read: 0: invalid number ./bash: line 0: declare: REPLY: not found #2 adopt the same semantics as POSIX read(2) syscall http://pubs.opengroup.org/onlinepubs/9699919799/functions/read.html describes: | Before any action described below is taken, and if nbyte is zero, the read() | function may detect and return errors as described below. In the absence of | errors, or if error detection is not performed, the read() function shall | return zero and have no other results. This is what the rest of the shells that support a similar option do: dualbus@debian:~$ for sh in bash ksh93 mksh zsh; do echo $sh $($sh -c 'set -- -n 0; [ -n "$ZSH_VERSION" ] && set -k 0; read "$@" REPLY <<< abc; typeset -p REPLY'); done bash declare -- REPLY="abc" ksh93 REPLY='' mksh typeset REPLY= zsh typeset REPLY='' I'm in favour of #2. This was reported by Freenode user `mknod' in #bash
