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|
#! /bin/bash
#
#From: kaz@cafe.net (Kaz Kylheku)
#Newsgroups: comp.unix.shell
#Subject: Funky little bash script
#Message-ID: <6mspb9$ft2@espresso.cafe.net>
#Date: Thu, 25 Jun 1998 06:11:39 GMT
#Here is something I wrote a few years ago when I was bored one day.
#Warning: this contains control characters.
# Line input routine for GNU Bourne-Again Shell
# plus terminal-control primitives.
#
# by Kaz Kylheku
# June 1996, Vancouver, Canada
#
# Function to disable canonical input processing.
# Terminal modes are saved into variable "savetty"
#
#
function raw
{
savetty=$(stty -g)
stty -icanon -isig -echo -echok -echonl inlcr
}
#
# Function to restore terminal settings from savetty variable
#
function restore
{
stty $savetty
}
#
# Set terminal MIN and TIME values.
# If the input argument is a zero, set up terminal to wait for
# a keystroke indefinitely. If the argument is non-zero, set up
# an absolute timeout of that many tenths of a second. The inter-keystroke
# timer facility of the terminal driver is not exploited.
#
function settimeout
# $1 = tenths of a second
{
if [ "$1" = "0" ] ; then
min=1
timeout=0
else
min=0
timeout="$1"
fi
stty min $min time $timeout
unset min timeout
}
#
# Input a single key using 'dd' and echo it to standard output.
# Launching an external program to get a single keystroke is a bit
# of a pig, but it's the best you can do! Maybe we could convince the
# GNU guys to make 'dd' a bash builtin.
#
function getkey
{
eval $1="\"\$(dd bs=1 count=1 2> /dev/null)\""
}
#
# Input a line of text gracefully.
# The first argument is the name of a variable where the input line is
# to be stored. If this variable is not empty, its contents are printed
# and treated as though the user had entered them.
# The second argument gives the maximum length of the input line; if it
# is zero, the input is unlimited (bad idea).
# ^W is used to delete words
# ^R redraws the line at any time by backspacing over it and reprinting it
# ^U backspaces to the beginning
# ^H or ^? (backspace or del) delete a single character
# ^M (enter) terminates the input
# all other control keys are ignored and cause a beep when pressed
#
#
function getline
{
settimeout 0 # No keystroke timeout.
save_IFS="$IFS" # Save word delimiter and set it to
IFS="" # to null so ${#line} works correctly.
eval line=\${$1} # Fetch line contents
echo -n "$line" # and print the existing line.
while [ 1 ] ; do
getkey key # fetch a single keystroke
case "$key" in
| ) # BS or DEL
if [ ${#line} != 0 ] ; then # if line not empty
echo -n " " # print destructive BS
line="${line%%?}" # chop last character
else # else if line empty
echo -n # beep the terminal
fi
;;
) # kill to line beg
while [ ${#line} != 0 ] ; do # while line not empty
echo -n " " # print BS, space, BS
line="${line%?}" # shorten line by 1
done
;;
) # redraw line
linesave="$line" # save the contents
while [ ${#line} != 0 ] ; do # kill to line beg
echo -n " "
line="${line%?}"
done
echo -n "$linesave" # reprint, restore
line="$linesave"
unset linesave # forget temp var
;;
)
while [ "${line% }" != "$line" ] && [ ${#line} != 0 ] ; do
echo -n " "
line="${line%?}"
done
while [ "${line% }" = "$line" ] && [ ${#line} != 0 ] ; do
echo -n " "
line="${line%?}"
done
;;
| | | | | | | | | | |
)
echo -n # ignore various control characters
;; # with an annoying beep
| | | | | | | | | | | | )
echo -n
;;
' ' | | | | | )
echo -n
;;
'' ) # Break out of loop on carriage return.
echo # Send a newline to the terminal.
break # (Also triggered by NUL char!).
;;
* ) # Append character to the end of the line.
# If length is restricted, and the line is too
# long, then beep...
if [ "$2" != 0 ] && [ $(( ${#line} >= $2 )) = 1 ] ; then
echo -n
else # Otherwise add
line="$line$key" # the character.
echo -n "$key" # And echo it.
fi
;;
esac
done
eval $1=\"\$line\"
IFS="$save_IFS"
unset line save_IFS
}
# uncomment the lines below to create a standalone test program
#
echo "Line input demo for the GNU Bourne-Again Shell."
echo "Hacked by Kaz Kylheku"
echo
echo "Use ^H/Backspace/Del to erase, ^W to kill words, ^U to kill the"
echo "whole line of input, ^R to redraw the line."
echo "Pass an argument to this program to prime the buffer contents"
raw
echo -n "go: "
if [ ${#1} != 0 ] ; then
LINE=$1
fi
getline LINE 50
restore
echo "<$LINE>"
|
