477 lines
9.7 KiB
Bash
477 lines
9.7 KiB
Bash
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#!/bin/sh
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# this is a line editor using only /bin/sh, /bin/dd and /bin/rm
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# /bin/rm is not really required, but it is nice to clean up temporary files
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PATH=
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dd=/bin/dd
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rm=/bin/rm
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# temporary files we might need
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tmp=/tmp/silly.$$
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ed=/tmp/ed.$$
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trap "$rm -f $tmp $tmp.1 $tmp.2 $tmp.3 $tmp.4 $tmp.5 $tmp.6 $ed.a $ed.b $ed.c; exit" 0 1 2 3
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# from now on, no more rm - the above trap is enough
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unset rm
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# we do interesting things with IFS, but better save it...
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saveIFS="$IFS"
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# in case "echo" is not a shell builtin...
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Echo () {
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case "$1" in
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-n) shift
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$dd of=$tmp 2>/dev/null <<EOF
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$@
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EOF
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IFS="+"
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set `$dd if=$tmp bs=1 of=/dev/null skip=1 2>&1`
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IFS="$saveIFS"
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$dd if=$tmp bs=1 count=$1 2>/dev/null
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;;
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*) $dd 2>/dev/null <<EOF
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$@
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EOF
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;;
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esac
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}
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# this is used to generate garbage files
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true () {
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return 0
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}
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false () {
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return 1
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}
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zero () {
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( trap 'go=false' 13
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go=true
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while $go
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do
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$dd "if=$0"
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case "$?" in
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0) ;;
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*) go=false ;;
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esac
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done
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) 2>/dev/null
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}
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# arithmetic using dd!
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# add variable n1 n2 n3...
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# assigns n1+n2+n3+... to variable
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add () {
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result="$1"
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shift
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$dd if=/dev/null of=$tmp bs=1 2>/dev/null
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for n in "$@"
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do
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case "$n" in
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0) ;;
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*) zero | $dd of=$tmp.1 bs=1 "count=$n" 2>/dev/null
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( $dd if=$tmp; $dd if=$tmp.1 ) 2>/dev/null | $dd of=$tmp.2 2>/dev/null
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$dd if=$tmp.2 of=$tmp 2>/dev/null
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;;
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esac
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done
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IFS="+"
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set `$dd if=$tmp bs=1 of=/dev/null 2>&1`
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IFS="$saveIFS"
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eval $result='$1'
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}
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# subtract variable n1 n2
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# subtracts n2 from n1, assigns result to variable
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subtract () {
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result="$1"
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zero | $dd of=$tmp bs=1 "count=$2" 2>/dev/null
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IFS="+"
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set `$dd if=$tmp bs=1 of=/dev/null "skip=$3" 2>&1`
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IFS="$saveIFS"
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case "$1" in
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dd*) set 0 ;;
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esac
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eval $result='$1'
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}
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# multiply variable n1 n2
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# variable = n1 * n2
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multiply () {
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result="$1"
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zero | $dd "bs=$2" of=$tmp "count=$3" 2>/dev/null
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IFS="+"
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set `$dd if=$tmp bs=1 of=/dev/null 2>&1`
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IFS="$saveIFS"
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eval $result='$1'
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}
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# divide variable n1 n2
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# variable = int( n1 / n2 )
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divide () {
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result="$1"
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zero | $dd bs=1 of=$tmp "count=$2" 2>/dev/null
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IFS="+"
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set `$dd if=$tmp "bs=$3" of=/dev/null 2>&1`
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IFS="$saveIFS"
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eval $result='$1'
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}
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# compare variable n1 n2 sets variable to lt if n1<n2, gt if n1>n2, eq if n1==n2
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compare () {
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res="$1"
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n1="$2"
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n2="$3"
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subtract somename "$n1" "$n2"
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case "$somename" in
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0) ;;
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*) eval $res=gt; return;
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esac
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subtract somename "$n2" "$n1"
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case "$somename" in
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0) ;;
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*) eval $res=lt; return;
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esac
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eval $res=eq
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}
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# lt n1 n2 returns true if n1 < n2
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lt () {
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n1="$1"
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n2="$2"
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subtract somename "$n2" "$n1"
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case "$somename" in
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0) return 1 ;;
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esac
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return 0
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}
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# le n1 n2 returns true if n1 <= n2
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le () {
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n1="$1"
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n2="$2"
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subtract somename "$n1" "$n2"
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case "$somename" in
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0) return 0 ;;
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esac
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return 1
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}
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# gt n1 n2 returns true if n1 > n2
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gt () {
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n1="$1"
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n2="$2"
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subtract somename "$n1" "$n2"
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case "$somename" in
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0) return 1 ;;
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esac
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return 0
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}
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# ge n1 n2 returns true if n1 >= n2
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ge () {
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n1="$1"
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n2="$2"
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subtract somename "$n2" "$n1"
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case "$somename" in
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0) return 0 ;;
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esac
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return 1
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}
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# useful functions for the line editor
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# open a file - copy it to the buffers
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open () {
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file="$1"
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set `$dd "if=$file" of=/dev/null 2>&1`
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case "$1" in
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dd*) return 1
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esac
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# copy the first line to $ed.c
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go=true
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len=0
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while $go
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do
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case "`$dd "if=$file" bs=1 skip=$len count=1 2>/dev/null`" in
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?*) go=true ;;
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*) go=false ;;
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esac
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add len 1 $len
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done
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# now $len is the length of the first line (including newline)
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$dd "if=$file" bs=1 count=$len of=$ed.c 2>/dev/null
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$dd "if=$file" bs=1 skip=$len of=$ed.b 2>/dev/null
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$dd if=/dev/null of=$ed.a 2>/dev/null
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lineno=1
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}
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# save a file - copy the buffers to the file
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save () {
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# make a backup copy of the original
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$dd "if=$1" "of=$1.bak" 2>/dev/null
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# and save
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( $dd if=$ed.a; $dd if=$ed.c; $dd if=$ed.b ) > "$1" 2>/dev/null
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}
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# replace n1 n2 bla replaces n2 chars of current line, starting n1-th
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replace () {
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$dd if=$ed.c of=$tmp.1 bs=1 "count=$1" 2>/dev/null
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( $dd if=$ed.c "skip=$1" bs=1 | $dd of=$tmp.2 bs=1 "skip=$2" ) 2>/dev/null
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shift
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shift
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( $dd if=$tmp.1; Echo -n "$@"; $dd if=$tmp.2 ) > $tmp.3 2>/dev/null
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$dd if=$tmp.3 of=$ed.c 2>/dev/null
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}
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# rstring n s bla
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# replace the n-th occurence of s with bla
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rstring () {
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n="$1"
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shift;
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# first we have to find it - this is fun!
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# we have $tmp.4 => text before string, $tmp.5 => text after
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$dd if=/dev/null of=$tmp.4 2>/dev/null
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$dd if=$ed.c of=$tmp.5 2>/dev/null
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string="$1"
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shift
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$dd of=$tmp.6 2>/dev/null <<EOF
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$@
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EOF
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while :
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do
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case "`$dd if=$tmp.5 2>/dev/null`" in
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$string*)
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if lt $n 2
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then
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# now we want to replace the string
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Echo -n "$@" > $tmp.2
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Echo -n "$string" > $tmp.1
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IFS="+"
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set `$dd bs=1 if=$tmp.1 of=/dev/null 2>&1`
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IFS="$saveIFS"
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slen=$1
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IFS="+"
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( $dd if=$tmp.4; $dd if=$tmp.2; $dd if=$tmp.5 bs=1 skip=$slen ) \
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2>/dev/null > $tmp
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$dd if=$tmp of=$ed.c 2>/dev/null
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return 0
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else
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subtract n $n 1
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( $dd if=$tmp.4; $dd if=$tmp.5 bs=1 count=1 ) > $tmp 2>/dev/null
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$dd if=$tmp of=$tmp.4 2>/dev/null
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# and remove it from $tmp.5
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$dd if=$tmp.5 of=$tmp bs=1 skip=1 2>/dev/null
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$dd if=$tmp of=$tmp.5 2>/dev/null
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fi
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;;
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?*) # add one more byte...
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( $dd if=$tmp.4; $dd if=$tmp.5 bs=1 count=1 ) > $tmp 2>/dev/null
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$dd if=$tmp of=$tmp.4 2>/dev/null
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# and remove it from $tmp.5
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$dd if=$tmp.5 of=$tmp bs=1 skip=1 2>/dev/null
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$dd if=$tmp of=$tmp.5 2>/dev/null
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;;
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*) # not found
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return 1
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;;
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esac
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done
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}
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# skip to next line
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next () {
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add l $lineno 1
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( $dd if=$ed.a; $dd if=$ed.c ) 2>/dev/null > $tmp.3
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$dd if=$ed.b of=$tmp.4 2>/dev/null
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open $tmp.4
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$dd if=$tmp.3 of=$ed.a 2>/dev/null
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lineno=$l
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}
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# delete current line
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delete () {
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l=$lineno
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$dd if=$ed.a 2>/dev/null > $tmp.1
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$dd if=$ed.b of=$tmp.2 2>/dev/null
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open $tmp.2
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$dd if=$tmp.1 of=$ed.a 2>/dev/null
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lineno=$l
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}
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# insert before current line (without changing current)
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insert () {
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( $dd if=$ed.a; Echo "$@" ) 2>/dev/null > $tmp.1
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$dd if=$tmp.1 of=$ed.a 2>/dev/null
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add lineno $lineno 1
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}
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# previous line
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prev () {
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case "$lineno" in
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1) ;;
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*) subtract lineno $lineno 1
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# read last line of $ed.a
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IFS='+'
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set `$dd if=$ed.a of=/dev/null bs=1 2>&1`
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IFS="$saveIFS"
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size=$1
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# empty?
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case "$size" in
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0) return ;;
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esac
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subtract size $size 1
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# skip final newline
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case "$size" in
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0) ;;
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*) subtract size1 $size 1
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case "`$dd if=$ed.a bs=1 skip=$size count=1 2>/dev/null`" in
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?*) ;;
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*) size=$size1 ;;
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esac
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;;
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esac
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go=true
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while $go
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do
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case "$size" in
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0) go=false ;;
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*) case "`$dd if=$ed.a bs=1 skip=$size count=1 2>/dev/null`" in
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?*) go=true; subtract size $size 1 ;;
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*) go=false; add size $size 1 ;;
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esac
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;;
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esac
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done
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# now $size is the size of the first n-1 lines
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# add $ed.c to $ed.b
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( $dd if=$ed.c; $dd if=$ed.b ) 2>/dev/null > $tmp.5
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$dd if=$tmp.5 of=$ed.b 2>/dev/null
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# move line to ed.c
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case "$size" in
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0) $dd if=$ed.a of=$ed.c 2>/dev/null
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$dd if=/dev/null of=$tmp.5 2>/dev/null
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;;
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*) $dd if=$ed.a of=$ed.c bs=1 skip=$size 2>/dev/null
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$dd if=$ed.a of=$tmp.5 bs=1 count=$size 2>/dev/null
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;;
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esac
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# move rest to ed.a
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$dd if=$tmp.5 of=$ed.a 2>/dev/null
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;;
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esac
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}
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# goes to a given line
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goto () {
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rl="$1"
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compare bla "$rl" $lineno
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case "$bla" in
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eq) return
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;;
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gt) while gt "$rl" $lineno
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do
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next
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done
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||
|
|
;;
|
||
|
|
lt) while lt "$rl" $lineno
|
||
|
|
do
|
||
|
|
prev
|
||
|
|
done
|
||
|
|
;;
|
||
|
|
esac
|
||
|
|
}
|
||
|
|
|
||
|
|
lineout () {
|
||
|
|
Echo -n "$lineno: "
|
||
|
|
$dd if=$ed.c 2>/dev/null
|
||
|
|
}
|
||
|
|
|
||
|
|
state=closed
|
||
|
|
name=
|
||
|
|
autoprint=true
|
||
|
|
|
||
|
|
while true
|
||
|
|
do
|
||
|
|
Echo -n '> '
|
||
|
|
read cmd arg
|
||
|
|
case "$cmd:$state" in
|
||
|
|
open:open) Echo "There is a file open already" ;;
|
||
|
|
open:*) if open "$arg"
|
||
|
|
then state=open; name="$arg"; $autoprint
|
||
|
|
else Echo "Cannot open $arg"
|
||
|
|
fi
|
||
|
|
;;
|
||
|
|
new:open) Echo "There is a file open already" ;;
|
||
|
|
new:*) open "$arg"
|
||
|
|
state=open
|
||
|
|
name="$arg"
|
||
|
|
$autoprint
|
||
|
|
;;
|
||
|
|
close:changed) Echo "Use 'discard' or 'save'" ;;
|
||
|
|
close:closed) Echo "Closed already" ;;
|
||
|
|
close:*) state=closed ;;
|
||
|
|
save:closed) Echo "There isn't a file to save" ;;
|
||
|
|
save:*) case "$arg" in
|
||
|
|
?*) save "$arg" ;;
|
||
|
|
*) save "$name" ;;
|
||
|
|
esac
|
||
|
|
state=open
|
||
|
|
;;
|
||
|
|
discard:changed) Echo "Your problem!"; state=closed ;;
|
||
|
|
discard:*) state=closed ;;
|
||
|
|
print:closed) Echo "No current file" ;;
|
||
|
|
print:*) lineout ;;
|
||
|
|
goto:closed) Echo "No current file" ;;
|
||
|
|
goto:*) goto "$arg"; $autoprint ;;
|
||
|
|
next:closed) Echo "No current file" ;;
|
||
|
|
next:*) next; $autoprint ;;
|
||
|
|
prev:closed) Echo "No current file" ;;
|
||
|
|
prev:*) prev; $autoprint ;;
|
||
|
|
name:closed) Echo "No current file" ;;
|
||
|
|
name:*) name="$arg" ;;
|
||
|
|
replace:closed) Echo "No current file" ;;
|
||
|
|
replace:*) if rstring 1 $arg
|
||
|
|
then state=changed; $autoprint
|
||
|
|
else Echo "Not found"
|
||
|
|
fi
|
||
|
|
;;
|
||
|
|
nreplace:closed) Echo "No current file" ;;
|
||
|
|
nreplace:*) if rstring $arg
|
||
|
|
then state=changed; $autoprint
|
||
|
|
else Echo "Not found"
|
||
|
|
fi
|
||
|
|
;;
|
||
|
|
delete:closed) Echo "No current file" ;;
|
||
|
|
delete:*) delete; state=changed; $autoprint ;;
|
||
|
|
insert:closed) Echo "No current file" ;;
|
||
|
|
insert:*) insert "$arg"; prev; state=changed; $autoprint ;;
|
||
|
|
quit:changed) Echo "Use 'save' or 'discard'" ;;
|
||
|
|
quit:*) Echo "bye"; exit;;
|
||
|
|
autoprint:*) autoprint="lineout" ;;
|
||
|
|
noprint:*) autoprint="" ;;
|
||
|
|
:*) ;;
|
||
|
|
*) Echo "Command not understood" ;;
|
||
|
|
esac
|
||
|
|
done
|
||
|
|
|