Hello Emanuele,
Emanuele Torre wrote:
I have noticed that ed -p '' errors with the following error.
Thank you for reporting this, and for your accurate diagnostic of the cause
of the behavior of ed.
That seems incorrect; there does not seem to be anything in the
POSIX Issue 7 specification for ed that allows unspecified behaviour
when the prompt string is empty or requires that the prompt string
specified by -p shall not be the empty string.
Note that empty option-arguments are ambiguous. See item 2a of section '12.1
Utility Argument Syntax':
https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap12.html#tag_12_01
"a. If the SYNOPSIS of a standard utility shows an option with a mandatory
option-argument (as with [ -c option_argument] in the example), a conforming
application shall use separate arguments for that option and its
option-argument. However, a conforming implementation shall also permit
applications to specify the option and option-argument in the same argument
string without intervening <blank> characters."
How should ed interpret the following command line?:
ed -p"" foo
Until the above ambiguity is solved (if it is even possible), I think ed's
current behavior is the safest compromise.
Best regards,
Antonio.
