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Full Discussion: Is it possible in a shell script to modify itself ??
Top Forums Shell Programming and Scripting Is it possible in a shell script to modify itself ?? Post 67377 by TioTony on Tuesday 22nd of March 2005 10:40:31 PM
Old 03-22-2005
I have done something similar in a college AI class where we looked at the efficiency of different languages for AI. I wrote a script that replaced the file it was run from with new code, then ran the new script. Once the scirpt is running you can blow away it's file on disk since it is running from a copy in memory. I think you could pursue two methods to get the results you want.

1. In the script create a procedure that contains the entire text of the script itself and echo's it to $0 (this is the name of the file that was run in the first place). Then just run the procedure and have another section of code spit the new answers into the file as well.

2. Use a unique comment on the end of the lines containing the answers. Use sed to add/remove/modify lines in this section with the new answers from within the script.

This will work but using an external text file is probably a better way to go.
 

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LEARN ABOUT SUNOS

script

script(1)							   User Commands							 script(1)

NAME

       script - make record of a terminal session

SYNOPSIS

       script [-a] [filename]

DESCRIPTION

       The  script  utility  makes a record of everything printed on your screen. The record is written to filename. If no file name is given, the
       record is saved in the file typescript. See WARNINGS.

       The script command forks and creates a sub-shell, according to the value of $SHELL, and records the text from this session. The script ends
       when the forked shell exits or when Control-d is typed.

OPTIONS

       The following option is supported:

       -a	Appends the session record to filename, rather than overwriting it.

NOTES

       script places everything that appears on the screen in filename, including prompts.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsu			   |
       +-----------------------------+-----------------------------+
       |CSI			     |Enabled			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       attributes(5)

WARNINGS

       script  can  pose  a  security risk when used in directories that are writable by other users (for example, /tmp), especially when run by a
       privileged user, that is, root. Be sure that typescript is not a link before running script.

SunOS 5.10							    30 Jan 2004 							 script(1)
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