https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81421
--- Comment #15 from martin <mfe at live dot de> --- You are right! I did: sed '/^package /q' < /media/gcc-7.1.0/libgo/go/runtime/mksizeclasses.go > FILE /go/runtime/mksizeclasses.go > FILE The grep command "grep '^// +build ' FILE" printed nothing. Also egrep and fgrep are symlinks to grep: /bin/grep whereis egrep egrep: /bin/egrep ls /bin/egrep -lah lrwxrwxrwx 1 root root Jun 29 11:42 /bin/egrep -> grep ls /bin/fgrep -lah lrwxrwxrwx 1 root root Jun 29 11:42 /bin/fgrep -> grep The command env doesn't list GREP_OPTIONS.