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IRC client written in pure bash using only bash builtin commands and no other binaries.
#!/bin/bash
#no PATH, no way to accidently run any programs
PATH=''
#useful variables
term_height=0
term_width=0
term_scroll_height=0
status_line_row=0
irc_host=''
irc_channel=''
irc_nick=''
function scroll_bottom() {
echo -en '\e[999B'
}
#figure out terminal height, NOTE: moves cursor to bottom of terminal
function term_height() {
echo -en '\e[999B\e[6n'
read -s -r -d'['
read -s -r -d';' term_height
read -s -r -d'R' term_width
echo -en '\e[999D'
}
#set the area the terminal is allowed to scroll in
function scroll_helper() {
term_scroll_height=$((term_height-2))
status_line_row=$((term_height-1))
echo -en "\e[0;${term_scroll_height}r"
}
function bottom_line() {
echo -en "\e[${term_height};0f"
}
function paste_data() {
echo -en '\e7' "\e[${term_scroll_height};0f" '\n'
echo -n " $1"
echo -en '\e8'
}
function status_line() {
echo -en '\e7' "\e[${status_line_row};0f" '\e[2K'
echo -en "\e[4;44mSTATUS: $irc_nick in $irc_channel @ $irc_host\e[0m"
echo -en '\e8'
}
function init_screen() {
echo -en '\e[r' #reset screen
term_height
scroll_helper
bottom_line
}
function net_fd_helper() {
local buff=''
#close 44 if open, then open read/write
exec 44>&-
exec 44<>"$1"
#delay slightly to improve chance of success
#read -s -r -t1 -u 44
#try connecting, sometimes JOIN won't work here and will have to be done manually
echo "NICK $irc_nick" >&44
echo "USER $irc_nick 8 * :${HOSTNAME} ${USER}" >&44
echo "JOIN $irc_channel" >&44
while true
do
while IFS='' read -s -r -t1 -u 44
do
case "$REPLY" in
( :irc* )
paste_data "$REPLY"
;;
( PING* )
paste_data "$REPLY"
buff="${REPLY##*:}"
paste_data "PONG :$buff"
echo "PONG :$buff" >&44
;;
( * )
buff="${REPLY%%\!*}"
REPLY="${REPLY#*:*:}"
buff="<${buff/:/}> $REPLY"
paste_data "$buff"
;;
esac
done
while IFS='' read -r -t1
do
status_line
echo -en '\e[2K\r> '
case "$REPLY" in
( :shell* )
buff="${REPLY#*\ }"
paste_data "$buff"
eval "$buff"
;;
( :reset )
init_screen
break
;;
( /JOIN* )
irc_channel="${REPLY##*\ }"
echo "${REPLY/\//}" >&44
;;
( /QUIT* )
echo "QUIT :${REPLY#*\ }" >&44
exec 44>&-
exit 0
;;
( /* )
echo "${REPLY/\//}" >&44
;;
( "" )
break
;;
( * )
echo "PRIVMSG $irc_channel :$REPLY" >&44
;;
esac
buff="<$irc_nick> ${REPLY}"
paste_data "$buff"
done
done
}
function main() {
local irc_fd=''
scroll_bottom
read -p 'IRC Server (eg irc.rizon.net): ' -e -r irc_host
read -p 'IRC Channel (eg #foobar): ' -e -r irc_channel
read -p 'IRC Nickname (eg egg_lover): ' -e -r irc_nick
init_screen
net_fd_helper "/dev/tcp/$irc_host/6667"
}
main
@ghost

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commented Mar 28, 2016

Really interesting magic going on here. 👍

@daveloyall

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commented Mar 28, 2016

Regarding Line 4 (set PATH to empty string): How about absolute paths?

@SomeCrazyGuy

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commented Mar 29, 2016

@daveloyall I did it to prevent myself from running non-bash builtins

@Flonk

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commented Mar 29, 2016

That's really cool. Now do it in Batch!

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