Re: ed: please give me a little control over appending final newlines

[Andrew L. Moore]

In message <address@hidden>, Dan Jacobson writes:
>The ed manual says:
>       If a text (non-binary) file is not terminated by a newline
>       character,  then ed appends one on reading/writing it.  In
>       the case of a binary file, ed does not append a newline on
>       reading/writing.
>
The manual is ambiguous.  The source file `POSIX' explains more clearly:

    To assist in binary editing, when a file containing at least one ASCII
    NUL character is written, a newline is not appended if it did not
    already contain one upon reading.

>OK, please give me final control of this action thru a command line
>switch to override ed's choice if I need to.

A command-line switch is unnecessary.  Appending blank lines always
appends newlines. Suppressing the trailing newline can be done with
a command sequence such as:

    $ ed -s file <<EOF
    ?   r !dd if=/dev/zero bs=1 count=1 2>/dev/null
    ?   d
    ?   wq
    ? EOF
    $
      
I.e., append a "binary" file with no trailing newline - the output of
the dd command.  Subsequently deleting the appended file does not change
the "binary with no trailing newline" status.

>Don't just keep the decision behind my back with not even a definition
>of just exactly what ed believes are "text (non-binary) files".

ed never _removes_ characters from a file - even behind your back, and
when it inserts one during an interactive session, a diagnostic explicitly
states this.

>And, if it is so smart, why doesn't it know about what happens if you
>just add a NL to a CR-LF file?  I wouldn't complain if I had a way to
>control ed.

Format conversion is better handled separately:

#!/bin/sh -
#
#    @(#)jed
#
# This script is an ed(1) front-end for handling arbitrary file formats.
#
umask 077
PATH=/bin:/usr/bin:/usr/local/bin
 
TMP="unix-format.$$"
 
argv=""
while [ $# -ne 1 ]; do argv="$argv \"$1\""; shift; done
pathname="$1"
 
eval set -- "$argv"
 
case $(file "$pathname") in
*'CRLF line terminators'*)
    trap 'rm -f "$TMP"; exit' 0 1 2 15
    msdos2unix <"$pathname" >"$TMP"
    if [ ."$@" = . ]; then ed "$TMP"; else ed "$@" "$TMP"; fi
    unix2msdos <"$TMP" >"$pathname"
    ;;
*)
    if [ ."$@" = . ]; then ed "$pathname"; else ed "$@" "$pathname"; fi
    ;;
esac
# EOF

-AM