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sp4ke on 03/12/11

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Light sql like database written in Bash

/ Published in: Bash

This was a school project, so it is not well commented but feel free to ask details.

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##    This program is free software: you can redistribute it and/or modify
##    it under the terms of the GNU General Public License as published by
##    the Free Software Foundation, either version 3 of the License, or
##    (at your option) any later version.
##
##    This program is distributed in the hope that it will be useful,
##    but WITHOUT ANY WARRANTY; without even the implied warranty of
##    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
##    GNU General Public License for more details.
##
##    You should have received a copy of the GNU General Public License
##    along with this program.  If not, see <http://www.gnu.org/licenses/>.

#!/bin/sh
## bdsh.sh for bdsh in /u/all/benzia_a/cu/temp
## Made by chakib1 benziane
## Login   <benzia_a@epitech.net>
##
## Started on  Fri Jan 22 22:11:26 2010 chakib1 benziane
## Last update Fri Jan 22 22:57:44 2010 chakib1 benziane
##

### BDSH V1.0
### Database Emulator with Shell

### VARIABLES ####

TRUE=0
FALSE=1
E_NOARGS=68
VERBOSE=1
DB_FILE="sh.db"
DATABASE_HEADER="BDSH DATABASE V1.0\nLast modification:   `date`\n"
SEPARATOR='			@__:::__@			'
KEY=""
VALUE=""

#################################################
####       FUNCTIONS   ##########################
#################################################

usage ()
{
    echo "Syntax error : Usage" >&2
    cat<<EOF
bdsh.sh [-k] [(-f | -c) <db_file>] (put (<clef> | $<clef>) (<valeur> | $<clef>) |
                                    del (<clef> | $<clef>) [<valeur> | $<clef>] |
                                    select [<expr> | $<clef>]
				    flush)

EOF
}

file_error ()
{
    echo "No base found : $DB_FILE" >&2
    exit 1
}

set_output ()
{
    if [ ! -f "$DB_FILE" ]
    then
	echo "$DATABASE_HEADER" > "$DB_FILE"
    fi
}

db_put ()
{
    if [ -n "$1" ] && [ -n "$2" ]
    then
	KEY="$1"
	VALUE="$2"
	set_output
	if [ `echo "$VALUE" | grep '^\$.*$'` ]
	    then
	    VALUE=`echo "$VALUE" | sed 's/^\$$[^ ]*$/\1/g'`
	    SEARCH_VALUE=`grep "^$VALUE $SEPARATOR" "$DB_FILE"`
	    if [ -z "$SEARCH_VALUE" ]
	    then
		echo "No such key : \$<$VALUE>" >&2
		exit 1
	    else
		VALUE=`echo "$SEARCH_VALUE" | sed 's/.* $[^ ]*$$/\1/g'`
	    fi
	fi
	#### if in form $<key> ###
	if [ `echo "$KEY" | grep '^\$.*$'` ]
	    then
	    ### parse value of $key ###
	    KEY=`echo "$KEY" | sed 's/^\$$[^ ]*$/\1/g'`
	    SEARCH_KEY=`grep "^$KEY $SEPARATOR" "$DB_FILE"`
	    if [ -z "$SEARCH_KEY" ]
	    then		### KEY NOT FOUND ###
		echo "No such key : \$<$KEY>" >&2
		exit 1
	    else
				### KEY FOUND ###
		KEY=`echo "$SEARCH_KEY" | sed 's/.* $[^ ]*$$/\1/g'`
		SEARCH_KEY=`grep "^$KEY $SEPARATOR" "$DB_FILE"`
		if [ -z "$SEARCH_KEY" ]
		then
		    echo "$KEY $SEPARATOR $VALUE" >> "$DB_FILE"
		else
		    cat "$DB_FILE" | sed "/^$KEY $SEPARATOR/ s/[^ ]*$/$VALUE/g" > "$DB_FILE.temp"
		    cat $DB_FILE.temp > $DB_FILE && rm $DB_FILE.temp
		fi
	    fi
	    exit 0
	fi
	### KEY in form <KEY>
	SEARCH_KEY=`grep "^$KEY $SEPARATOR" "$DB_FILE"`
	if [ -n "$SEARCH_KEY" ]  ### if key exists
	then                     ### Replacing key
	    cat "$DB_FILE" | sed "/^$KEY / s/[^ ]*$/$VALUE/g" > "$DB_FILE.temp"
	    cat $DB_FILE.temp > $DB_FILE && rm $DB_FILE.temp
	else                     ### Creating new key
	    echo "$KEY $SEPARATOR $VALUE" >> "$DB_FILE"
	fi
    fi
}

db_del ()
{
    KEY="$1"
    VALUE="$2"
    ### if in form $key
    if [ `echo "$KEY" | grep '^\$.*$'` ]
    then
	    ### parse value of $key ###
	KEY=`echo "$KEY" | sed 's/^\$$[^ ]*$/\1/g'`
	SEARCH_KEY=`grep "^$KEY $SEPARATOR" "$DB_FILE"`
	KEY=`echo "$SEARCH_KEY" | sed 's/.* $[^ ]*$$/\1/g'`
    fi
    if [ -z "$2" ]
    then
	### searching key
	SEARCH_KEY=`grep "^$KEY $SEPARATOR" "$DB_FILE"`
	### KEY FOUND ###
	if [ -n "$SEARCH_KEY" ]
	    then
	    VALUE=`echo "$SEARCH_KEY" | sed 's/.* $[^ ]*$$/\1/g'`
	    cat "$DB_FILE" | sed "/^$KEY / s/[^ ]*$//g" > "$DB_FILE.temp"
	    cat $DB_FILE.temp > $DB_FILE && rm $DB_FILE.temp
	fi
    else
	### Detecting value form
    	if [ `echo "$VALUE" | grep '^\$.*$'` ]
	    then
	    VALUE=`echo "$VALUE" | sed 's/^\$$[^ ]*$/\1/g'`
	    SEARCH_VALUE=`grep "^$VALUE $SEPARATOR" "$DB_FILE"`
	    VALUE=`echo "$SEARCH_VALUE" | sed 's/.* $[^ ]*$$/\1/g'`
	fi
	if [ -n "$VALUE" ]
	then
	    cat "$DB_FILE" | sed "/^$KEY/d" > "$DB_FILE.temp"
	    cat $DB_FILE.temp > $DB_FILE && rm $DB_FILE.temp
	fi
    fi
    exit 0
}

db_select ()
{
    if [ ! $1 ]
    then
	cat "$DB_FILE" | sed "s/^.* $SEPARATOR //g"
	exit 0
    else
	KEY="$1"
	### case of $key
	if [ `echo "$KEY" | grep '^\$.*$'` ]
	then
	    ### parse value of $key ###
	    KEY=`echo "$KEY" | sed 's/^\$$[^ ]*$/\1/g'`
	    SEARCH_KEY=`grep "^$KEY $SEPARATOR" "$DB_FILE"`
	    KEY=`echo "$SEARCH_KEY" | sed 's/.* $[^ ]*$$/\1/g'`
	    SEARCH_KEY=`grep "^$KEY $SEPARATOR" "$DB_FILE"`
	    if [ -z "$SEARCH_KEY" ]
	    then
		echo "No such key : \$<$KEY>" >&2
		exit 1
	    fi
	    VALUE=`echo "$SEARCH_KEY" | sed 's/.* $[^ ]*$$/\1/g'`
	    if [ $VERBOSE = "0" ]
	    then
		echo "<$KEY>=<$VALUE>"
	    else
		echo "$VALUE"
	    fi
	    exit 0
	else
	    if [ $VERBOSE = "0" ]
	    then
		TMP=`grep ".*$KEY.* $SEPARATOR" "$DB_FILE"`
		if [ -z "$TMP" ]
		then
		    echo "$KEY="
		else
		    grep ".*$KEY.* $SEPARATOR" "$DB_FILE" | sed "s/ $SEPARATOR /=/g"
		fi
		exit 0
	    else
		grep ".*$KEY.* $SEPARATOR" "$DB_FILE"  | sed "s/^.* $SEPARATOR //g"
	    fi
	    exit 0
	fi
    fi
}

##################################################
#### PROGRAM STARTS HERE #########################
##################################################

if [ ! "$1" ]
then
    echo "Syntax error : put" >&2
    exit $E_NOARGS
fi

while [ $# -gt 0 ]; do
    case "$1" in
	-k)
	    VERBOSE=0
	    ;;
	-c|-f)
	    DB_FILE="$2"
	    if [ -n "$2" ]
		then
		if [ ! -f "$DB_FILE" ] && [ "$1" = "-f" ]
		then
		    echo "No base found : $DB_FILE " >&2
		    exit 1
		else
		    shift
		fi
	    else
		usage
		exit $E_NOARGS
	    fi
	    ;;
	-*)
	    usage
	    exit $E_NOARGS
	    ;;
	put)
	    if [ $# -ne 3 ]
		then
		echo "Syntax error : put" >&2
		exit 1
	    else
		db_put "$2" "$3"
		shift;shift
	    fi
	    ;;
	del)
	    if [ -n "$2" ] && [ ! $4 ]
	    then
		db_del "$2" "$3"
		shift;shift
	    else
		echo "Syntax error : put" >&2
		exit $E_NOARGS
	    fi
	    ;;
	select)
	    if [ $# -lt 3 ]
	    then
		db_select "$2"
		shift
		exit 0
	    else
		echo "Syntax error : select" >&2
		exit $E_NOARGS
	    fi
	    ;;
	flush)
	    if [ "$#" -eq "1" ]
	    then
		echo "$DATABASE_HEADER" > "$DB_FILE"
		exit 0
	    else
		usage
		exit $E_NOARGS
	    fi
	    ;;
	*)
	    usage
	    break;;
    esac
    shift
done

#END

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