Shell Programming and Scripting

#!/bin/sh -

# @(#) s3       Demonstrate read one character in shell.
# See man stty and
# http://cs.senecac.on.ca/~lczegel/UNX510/lectures/Lecture6.html
# for some details.

echo
echo "(Versions displayed with local utility \"version\")"
version >/dev/null 2>&1 && version "=o" $(_eat $0 $1) stty dd
set -o nounset

echo
string=""
oldsettings=$(stty -g)
stty -icanon min 1 time 0 -icrnl -echo

i=0
printf " Enter your string:\n"
while :
do
  ch=$(dd bs=1 count=1 2> /dev/null)
  printf "$ch"
  i=`expr $i + 1`
  if [ $i -gt 3 ]
  then
    printf " \nToo many characters, kept only 3: \"$string\".\n"
        break
  fi
  string="${string}$ch"
done

stty $oldsettings
echo " Final value of string is \"$string\""

exit 0

$ ./s3

(Versions displayed with local utility "version")
AIX 1
sh - no version provided for /usr/bin/sh.
stty - no version provided for /usr/bin/stty.
dd - no version provided for /usr/bin/dd.

 Enter your string:
abcd
Too many characters, kept only 3: "abc".
 Final value of string is "abc"

#!/bin/sh -

# @(#) s4       Demonstrate read one character in shell.
# See man stty and
# http://cs.senecac.on.ca/~lczegel/UNX510/lectures/Lecture6.html
# for some details.

echo
echo "(Versions displayed with local utility \"version\")"
version >/dev/null 2>&1 && version "=o" $(_eat $0 $1) stty dd
set -o nounset

echo
string=""
oldsettings=$(stty -g)
stty -icanon min 1 time 0 -icrnl -echo

i=0
last=false
printf " Enter your string:\n"
while :
do
  ch=$(dd bs=1 count=1 2> /dev/null)
  printf "$ch"
  # To get a real "^M" with vi/vim, use control-v control-Enter.
 ]]f [[ "$ch" =
  then
    printf "\n"
    last=true
  else
    string="${string}$ch"
    i=$( expr $i + 1 )
    if [[ $i -ge 3 ]]
    then
          printf "\n"
      last=true
    fi
  fi
  if [ $last = true ]
  then
    break
  fi
done

stty $oldsettings
echo " Final value of string is \"$string\""

exit 0

aix drl 405 $ ./s4

(Versions displayed with local utility "version")
aix 5.1
sh - no version provided for /usr/bin/sh.
stty - no version provided for /usr/bin/stty.
dd - no version provided for /usr/bin/dd.

 Enter your string:
abc
 Final value of string is "abc"
aix drl 405 $
aix drl 405 $ ./s4

(Versions displayed with local utility "version")
aix 5.1
sh - no version provided for /usr/bin/sh.
stty - no version provided for /usr/bin/stty.
dd - no version provided for /usr/bin/dd.

 Enter your string:
xy
 Final value of string is "xy"