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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:
 

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echo(1B)					     SunOS/BSD Compatibility Package Commands						  echo(1B)

NAME
echo - echo arguments to standard output SYNOPSIS
/usr/ucb/echo [-n] [argument] DESCRIPTION
echo writes its arguments, separated by BLANKs and terminated by a NEWLINE, to the standard output. echo is useful for producing diagnostics in command files and for sending known data into a pipe, and for displaying the contents of envi- ronment variables. For example, you can use echo to determine how many subdirectories below the root directory (/) is your current directory, as follows: o echo your current-working-directory's full pathname o pipe the output through tr to translate the path's embedded slash-characters into space-characters o pipe that output through wc -w for a count of the names in your path. example% /usr/bin/echo "echo $PWD | tr '/' ' ' | wc -w" See tr(1) and wc(1) for their functionality. The shells csh(1), ksh(1), and sh(1), each have an echo built-in command, which, by default, will have precedence, and will be invoked if the user calls echo without a full pathname. /usr/ucb/echo and csh's echo() have an -n option, but do not understand back-slashed escape characters. sh's echo(), ksh's echo(), and /usr/bin/echo, on the other hand, understand the black-slashed escape characters, and ksh's echo() also understands a as the audible bell character; however, these commands do not have an -n option. OPTIONS
-n Do not add the NEWLINE to the output. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWscpu | +-----------------------------+-----------------------------+ SEE ALSO
csh(1), echo(1), ksh(1), sh(1), tr(1), wc(1), attributes(5) NOTES
The -n option is a transition aid for BSD applications, and may not be supported in future releases. SunOS 5.11 3 Aug 1994 echo(1B)
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