cygwin - Bash subshell for setting SHELLOPTS in a script -

this question not cygwin specific. however, in cygwin mail archive https://cygwin.com/ml/cygwin-announce/2010-08/msg00015.html various instructions setting cygwin specific igncr shellopt variable , 1 of them instruction:

4a. single affected script, add line after she-bang: ~ (set -o igncr) 2>/dev/null && set -o igncr; # comment needed

i understand set -o igncr sets igncr in shellopts. however, not understand why instruction includes invoking in subshell. understand, variables , environment of subshell not stick around in parent process. use of it?

the detail material here in command

(set -o igncr) 2>/dev/null && set -o igncr 

is context.

imagine shell script designed run on non-windows machines in cygwin.

normally (not under cygwin) use of set -o igncr error (as attempting set other invalid set option.

however, under cygwin set both meaningful , helpful.

so how write script operates in both places? need test current environment. check specific environment variables, specific paths, etc. or (and similar move away browser-sniffing , feature testing) can check whether current environment supports option attempting set.

so try set throws error if doesn't work try set in sub-shell (and toss error output /dev/null ignore it) , if (and if) set succeeds (&&) set in current shell environment well.