Script to switch console attached to a command (for Linux)

switch-tty.sh

#!/bin/bash

# For example:  switch-tty.sh `pidof vi` `tty`

target=$1
dest=$2
if [ -z "$target" -o -z "$dest" ]; then
    echo "usage: $0 pid target"
    exit 1
fi

current="$(readlink /proc/$target/fd/0)"
echo "Current stdin: $current"

if [ "$current" = "$dest" ]; then
    echo "no switch is required."
    exit 1
fi

tty>/dev/null < "$current" && srctty=1
tty>/dev/null < "$dest" && desttty=1
tty>/dev/null && istty=1
[ -n "$istty" -a "$(tty)" = "$dest" ] && thistty=1

fds=()
for x in /proc/$target/fd/*; do
    if [ "$current" = "$(readlink $x)" ]; then
	fd=${x##*/}
	fds=(${fds[@]} $fd)
    fi
done
echo "Target fds: ${fds[@]}"

leader=$( ps a | grep "${dest#/dev/}" | setsid grep Ss | cut -f 1 -d \  )
echo "session leader: $leader"

[ -n "$thistty" ] && echo "Switching to this TTY"

echo -n "Continue? (y/N) "
read
[ "$REPLY" != "y" -a "$REPLY" != "Y" ] && exit 2

( echo "p open(\"$dest\", 2)"; for x in ${fds[@]}; do echo "p dup2(\$1, $x)"; done; echo "p close(\$1)"; echo "detach"; echo "quit" ) | gdb -p $target

if [ -n "$srctty" -a -n "$desttty" ]; then
    stty -F $dest "$( stty -g -F "$current" )"
    [ -n "$thistty" ] && clear
    kill -STOP $leader
    kill -STOP $target
    sleep 1
    kill -CONT $target
    kill -WINCH $target
fi
[ -n "$thistty" ] && while :; do sleep 60; kill -0 $target || break; done