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BASH Shell script - help with read


 
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# 8  
Old 08-06-2009
The following will process the back arrow keys by removing the codes for these keys plus removing the previous character (since the codes are indicating this character should be deleted):

Code:
#!/bin/sh
read -rp "Command to execute: " the_command
while [ "`expr $the_command : '.*\(\[\).*'`" != "" ]
do
        echo "looping" >&2
        the_command=`echo $the_command | sed 's/.^[\[D//'`
done
echo "*$the_command*"
eval "$the_command"

The combination ^[ shown should actually be entered as an escape character. Notice we need a while loop - the /g switch will not work (at least not that I can see).

The problem with this is that it is specific to back arrow keys. If the person presses some other keys and tries to erase them with back arrow, this code may fail. The general problem of line editing can be messy.

Another approach would be to present the user with numbered menu items and check which menu item was selected. This would prevent mistyping the name of a program. The menu could be static or could even be generated dynamically by the shell script.
# 9  
Old 08-06-2009
tested cygwin ksh
Code:
while true
do
        echo -n "filename:"
        read  -r str
        # remove cursor keys
        some=${str//$'\x1b'[D/}
        some=${some//$'\x1b'[A/}
        some=${some//$'\x1b'[C/}
        some=${some//$'\x1b'[B/}
        [ "$str" != "$some" ] && echo "don't use array keys, only backspace" && continue
        break
done
#now str is okay
echo "$str"

Why read again ? = Wysewyg is not correct if data include cursor keys = not same what user has tried.

This enough in cygwin, but in generic version you need to read cursorkeys value using tput and remove those values.

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