#! /bin/sh
# #############################################################################

       NAME_="rotcmd"
       HTML_="rotate commands in a file"
    PURPOSE_="rotate commands listed in a file if file execution has been interrupted"
   SYNOPSIS_="$NAME_ [-hlm] <file>"
   REQUIRES_="standard GNU commands"
    VERSION_="1.0"
       DATE_="2003-04-12; last update: 2004-04-12"
     AUTHOR_="Dawid Michalczyk <dm@eonworks.com>"
        URL_="www.comp.eonworks.com"
   CATEGORY_="misc"
   PLATFORM_="Linux"
      SHELL_="bash"
 DISTRIBUTE_="yes"

# #############################################################################
# This program is distributed under the terms of the GNU General Public License

usage() {

echo >&2 "$NAME_ $VERSION_ - $PURPOSE_
Usage: $SYNOPSIS_
Requires: $REQUIRES_
Options:
     <file>, file with the commands
     -h, usage and options (this help)
     -m, manual
     -l, see this script"
    exit 1
}

manual() { echo >&2 "

NAME

    $NAME_ $VERSION_ - $PURPOSE_

SYNOPSIS

    $SYNOPSIS_

DESCRIPTION

    This script is useful in a situation when one has to regularly run
    multiple commands that are listed in a file and may have to stop the
    execution of the file before all commands are done executing. Upon
    next execution of the file, to avoid re-running the already run
    commands, one would have to manually re-arrange the commands.

    This script eliminates the need for that, as it acts as a wrapper to
    the commands listed in a file.

    If the execution of this script is interrupted, the commands stored in a
    file get rotated, so the commands which have already been executed will
    be appended to the end of the file. The only command that will be re
    executed is the one which did not finish running when the file execution
    was interrupted.

NOTE

    The last command in file must be terminated by a new line character.

AUTHOR

    $AUTHOR_ Suggestions and bug reports are welcome.
    For updates and more scripts visit $URL_

"; exit 1; }

# local funcs
rotate() {

    c=$(wc -l $tmp_1 | { read a b ; echo $a; } )
    c2=0
    while read line;do

        if (( c2 >= c ));then

            echo $line >> $tmp_2

        fi
        ((c2++))

    done < $a
    cat $tmp_2 $tmp_1 > $a
    rm -f $tmp_1 $tmp_2

}

# args check
[ $# -eq 0 ] && { echo >&2 missing argument, type $NAME_ -h for help; exit 1; }

# tmp file set up
tmp_1=/tmp/tmp.${RANDOM}$$
tmp_2=/tmp/tmp.${RANDOM}$$

# signal trapping and tmp file removal
trap 'rotate >/dev/null 2>&1' 0
trap "exit 1" 1 2 3 15

# arg handling and execution
case $1 in

    -h) usage ;;
    -m) manual ;;
    -l) more $0; exit 1 ;;
     *) # main execution

        for a in "$@";do
            if [ -f "$a" ]; then

                while read line;do

                    $line
                    echo $line >> $tmp_1

                done < $a

            else
                echo file $a does not exist
            fi
        done ;;

esac
rm -f $tmp_1