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Full Discussion: && and || operators
Top Forums Shell Programming and Scripting && and || operators Post 302956133 by Don Cragun on Saturday 26th of September 2015 11:19:57 PM
Old 09-27-2015
As sea said, your exit commands are exiting the subshell in which they're located; not the parent shell... But, you can reverse the condition and use multiple && operators with a single || operator. Try:
Code:
[[ $($adb_path devices|wc -l) -le 2 ]] && echo "please connect a device" && exit -1 || echo "there's a device connected"

However, just because you CAN do it this way doesn't mean that something more like:
Code:
if [[ $($adb_path devices|wc -l) -le 2 ]]
then	echo 'please connect a device'
	exit -1
fi
echo "there's a device connected"

wouldn't be better. This form is easier to read for most code readers and should run as fast or a tiny bit faster than the single line version.

Despite what sea said, a long command line can have more than one meaningful || operator if conditional code follows the first ||. For example:
Code:
x=$((number % 3))
[[ x -eq 0 ]] && echo 0 || [[ x -eq 1 ]] && echo 1 || echo 2

Last edited by Don Cragun; 09-27-2015 at 02:05 AM.. Reason: Fix typo: s/you're/your/
These 2 Users Gave Thanks to Don Cragun For This Post:
pandeesh sea
 

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LEARN ABOUT SUNOS

noecho

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 5.10							    5 Jun 2002							    echo(3XCURSES)
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