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BASH Shell script - help with read

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# 1  
Old 08-05-2009
BASH Shell script - help with read

Hi all,

I'm sure this is quite a simple problem, but i'm completely new to shell scripting, so bare with me. Having problems with the read command. Here's what I have:

read -rp "Command to execute: " the_command
echo "$the_command"
eval "$the_command"

Now, say, for instance the user enters the command to execute as echo "this is a test" - all works fine... the echo shows the correct command and the eval executes the command, echoing "this is a test".

BUT... if the user enters the command as echo "this id a typeo" - they go back to correct the mistake so that it now reads echo "this is a typeo" - now the script errors. The echo shows the correct command, but the eval has a problem. Is it possible that the variable the_command is getting every keystroke (including backspaces) and not just the final string? Can someone please help out a newbie Smilie

# 2  
Old 08-05-2009
Please copy and paste your script on here with code tags. What you posted works fine on my Solaris machine.
# 3  
Old 08-05-2009
read -rp "Command to execute: " the_command
echo "$the_command"
eval "$the_command"

Here's what happens:

$ ./
Command to execute: echo "cat"
echo "cat"
but now i enter the command as echo "cat" but realise it's supposed to be echo "ratty" so i use the left cursor and backspace to fix the typeo;

$ ./
Command to execute: echo "ratty"
echo "cat"
Eventually the script will be used to enter commands such as:
shake "c:\test\test.#.tiff" -t 1-100

The reason i need this to work is because I anticipate users will drag a file into the terminal to get the filepath, but will need to change the resulting filepath from "c:\test\test.tiff" to "c:\test\test.#.tiff" for the script to execute.

p.s. I should mention that i'm running the script through Cygwin on a Windows machine.
# 4  
Old 08-05-2009
Does the script have to be run by sh? Have you tried running it with ksh or bash?
# 5  
Old 08-05-2009
More generic version. Echo is echo and read is read.
echo -e "C.. execute:\c"
read the_command
# or read -r  # what you need ?  I think that editionkeys handling in read depends which shell you use. Why to use -r in this case ?
echo "$the_command"
eval "$the_command"

# 6  
Old 08-05-2009
Try using backspace instead of the left cursor key.

When I run it on Cygwin, it does not crash. However, it does not process correctly due to the codes generated by the left cursor key and I get the following:

./ line 4: $'cat\E[D\E[D\E[Dratty': command not found

# 7  
Old 08-05-2009
Firstly, thanks for the replies, guys.. i appreciate the help.

ilikecows: yes, changed it to #!/bin/bash but makes no difference.

kshji: I need to use the read -r option so that it interprets the "\" in inputted filepaths correctly.

mrtiller: If I just use backspace, you're right, it works.... However, I'm assuming the users of the script will not necessarily use backspace only and might do as I described and use the arrow keys and backspace - in which case I don't want the script to go funny on me.

I think you're right - it's not processing correctly due to the codes generated by the left cursor and going over the top of what was already there... is there any way I can tell it to ignore those keystrokes and just store the final string, no matter how it is created?

Cheers all,

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