A question for the AWK wizards

[Giorgos Keramidas]

On 2006-07-25 21:43, Murray Taylor <MTaylor at bytecraft.com.au> wrote:
> Hi all,
>
> I have a shell script which is called with an arbitrary message
> argument. Punctuation excludes * ? & | > < chars.
>
> It processes it via an AWK command line 'script' and dumps the result
> in a file for the SMS sender...
>
> Nice and simple.
>
> Except that the AWK script seems to duplicate the last character or
> two in the message. Everything else in the 200 odd lines of shell
> scripts surrounding this function run just fine, and this bit runs
> too, but this tiny thing is _VERY_ annoying.
>
> The shell code is listed below.
>
> Please teach me what bit I missed .... (C and TCL are my forte, not
> AWK)

> ------------------8<------------------------------
> # sourced into other scripts that need to SMS
> # !! 4 space indents, NOT tabs !!
> #
> # generate the sms message
> # the awk code forces the message to be < 160 chars
> sendsms() {
>     msg=$1
>
>     case ${sms_enable} in
>     [Yy][Ee][Ss])
>         for phone in ${phonelist}
>         do
>             tmpfile=`mktemp -t sms`
>             echo ${phone} >> ${tmpfile}
>             ${AWK} '{ printf "%-0.159s", $0 }' >> ${tmpfile} << EOF2
> `echo $msg`
> EOF2
>             mv ${tmpfile} ${gsmspool_dir}
>         done
>         ;;
>     *)
>         ;;
>     esac
> }

The above has a weird construct which can be simplified a bit:

    | ${AWK} '{ printf "%-0.159s", $0 }' >> ${tmpfile} << EOF2
    | `echo $msg`
    | EOF2

You can write this as:

    |  echo "${msg}" | ${AWK} '{printf "%-0.159s", $0}' >> "${tmpfile}"

Are you deliberately avoiding to append a newline character to the
output of ${AWK} above?  See the output of the two commands below,
as it's filtered through hd(1) utility.

    | $ echo foo | awk '{ printf "%-0.159s", $0 }' | hd
    | 00000000  66 6f 6f                                          |foo|
    | 00000003
    | $ echo foo | awk '{ printf "%-0.159s\n", $0 }' | hd
    | 00000000  66 6f 6f 0a                                       |foo.|
    | 00000004
    | $

There is no problem with this part of the scripts you posted though.
They should work as expected.  I'd probably look elsewhere for a bug
that causes the character duplication.