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Full Discussion: Grabbing value from command output and monitoring for changes
Top Forums Shell Programming and Scripting Grabbing value from command output and monitoring for changes Post 302447636 by agama on Monday 23rd of August 2010 11:07:25 PM
Old 08-24-2010
Quote:
Originally Posted by alister
Those suggestions will often fail, since some very popular shells (bash included) will run the read command at the end of the pipeline in a subshell. The value assigned to new_value will never be visible in the script's environment, since it will only ever exist in the subshell's environment (which is destroyed as soon as the read is completed).

Example using bash:
Code:
$ x=; echo hello | read x; echo $x

$ x=; echo hello | ( read x; echo $x ) 
hello

Regards,
Alister
Right about bash, however Ksh does the right thing and this will work in ksh.

Code:
$ cat t19
#!/usr/bin/env ksh
x= 
echo hello | read x 
echo $x

$ t19
hello

This User Gave Thanks to agama For This Post:
monty77
 

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LEARN ABOUT OPENSOLARIS

echo

echo(3XCURSES)						  X/Open Curses Library Functions					    echo(3XCURSES)

NAME

       echo, noecho - enable/disable terminal echo

SYNOPSIS

       cc [ flag... ] file... -I /usr/xpg4/include  -L	/usr/xpg4/lib 
	-R  /usr/xpg4/lib  -lcurses  [ library... ]

       c89 [ flag... ] file... -lcurses [ library... ]

       #include <curses.h>

       int echo(void);

       int noecho(void);

DESCRIPTION

       The  echo()  function enables Echo mode for the current screen. The noecho() function disables Echo mode for the current screen. Initially,
       curses software echo mode is enabled and hardware echo mode of the tty driver is disabled. The echo() and noecho() functions control  soft-
       ware echo only. Hardware echo must remain disabled for the duration of the application, else the behavior is undefined.

RETURN VALUES

       Upon successful completion, these functions return OK. Otherwise, they return ERR.

ERRORS

       No errors are defined.

ATTRIBUTES

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

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Unsafe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       getch(3XCURSES), getstr(3XCURSES), initscr(3XCURSES), libcurses(3XCURSES), scanw(3XCURSES), attributes(5), standards(5)

SunOS 5.11							    5 Jun 2002							    echo(3XCURSES)
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