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From: Robert Latest on 12 Jul 2010 14:00

Hello all,
quoting the "sh" manpage:

test expression

[ expression ]
The test utility evaluates the expression and, if it evaluates to
true, returns a zero (true) exit status; otherwise it returns 1
(false). If there is no expression, test also returns 1 (false).

All operators and flags are separate arguments to the test util‐
ity.

The following primaries are used to construct expression:

[...]


expression1 -a expression2
True if both expression1 and expression2 are true.

expression1 -o expression2
True if either expression1 or expression2 are true.

(expression) True if expression is true.


I've written a script that contains this line:

if [ ($last_seen -gt 0) -a ($last_seen -lt $toolate) ] ; then
# whatever
fi

It throws this syntax error:

test.sh: 23: Syntax error: word unexpected (expecting ")")

Why?


robert
From: Lew Pitcher on 12 Jul 2010 14:21
On July 12, 2010 14:00, in comp.unix.shell, boblatest(a)yahoo.com wrote:

>
> Hello all,
> quoting the "sh" manpage:
>
> test expression
>
> [ expression ]
> The test utility evaluates the expression and, if it evaluates
> to true, returns a zero (true) exit status; otherwise it
> returns 1
> (false). If there is no expression, test also returns 1
> (false).
>
> All operators and flags are separate arguments to the test
> util‐ ity.
>
> The following primaries are used to construct expression:
>
> [...]
>
>
> expression1 -a expression2
> True if both expression1 and expression2 are
> true.
>
> expression1 -o expression2
> True if either expression1 or expression2 are
> true.
>
> (expression) True if expression is true.
>
>
> I've written a script that contains this line:
>
> if [ ($last_seen -gt 0) -a ($last_seen -lt $toolate) ] ; then
> # whatever
> fi
>
> It throws this syntax error:
>
> test.sh: 23: Syntax error: word unexpected (expecting ")")
>
> Why?

Remember that the brackets need to be separate tokens

Instead of
if [ ($last_seen -gt 0) -a ($last_seen -lt $toolate) ] ; then
try
if [ ( $last_seen -gt 0 ) -a ( $last_seen -lt $toolate ) ] ; then



--
Lew Pitcher
Master Codewright & JOAT-in-training | Registered Linux User #112576
Me: http://pitcher.digitalfreehold.ca/ | Just Linux: http://justlinux.ca/
---------- Slackware - Because I know what I'm doing. ------


From: Chris F.A. Johnson on 12 Jul 2010 14:33
On 2010-07-12, Robert Latest wrote:
>
> Hello all,
> quoting the "sh" manpage:
>
> test expression
>
> [ expression ]
> The test utility evaluates the expression and, if it evaluates to
> true, returns a zero (true) exit status; otherwise it returns 1
> (false). If there is no expression, test also returns 1 (false).
>
> All operators and flags are separate arguments to the test util???
> ity.
>
> The following primaries are used to construct expression:
>
> [...]
>
>
> expression1 -a expression2
> True if both expression1 and expression2 are true.
>
> expression1 -o expression2
> True if either expression1 or expression2 are true.
>
> (expression) True if expression is true.
>
>
> I've written a script that contains this line:
>
> if [ ($last_seen -gt 0) -a ($last_seen -lt $toolate) ] ; then
> # whatever
> fi

Avoid -a and -o; use && and ||:

if [ $last_seen -gt 0 ] && [ $last_seen -lt $toolate ] ; then


--
Chris F.A. Johnson, author <http://shell.cfajohnson.com/>
===================================================================
Shell Scripting Recipes: A Problem-Solution Approach (2005, Apress)
Pro Bash Programming: Scripting the GNU/Linux Shell (2009, Apress)

From: Kenny McCormack on 12 Jul 2010 14:45
In article <8a15fuFhq1U1(a)mid.individual.net>,
Chris F.A. Johnson <cfajohnson(a)gmail.com> wrote:
....
> Avoid -a and -o; use && and ||:
>
>if [ $last_seen -gt 0 ] && [ $last_seen -lt $toolate ] ; then

Why?

(Not that I have any strong opinion on the matter, and I even agree with
you, but you usually have some obscure reason for your pronouncements)

--
"We should always be disposed to believe that which appears to us to be
white is really black, if the hierarchy of the church so decides."

- Saint Ignatius Loyola (1491-1556) Founder of the Jesuit Order -

From: Chris F.A. Johnson on 12 Jul 2010 15:12
On 2010-07-12, Kenny McCormack wrote:
> In article <8a15fuFhq1U1(a)mid.individual.net>,
> Chris F.A. Johnson <cfajohnson(a)gmail.com> wrote:
> ...
>> Avoid -a and -o; use && and ||:
>>
>>if [ $last_seen -gt 0 ] && [ $last_seen -lt $toolate ] ; then
>
> Why?
>
> (Not that I have any strong opinion on the matter, and I even agree with
> you, but you usually have some obscure reason for your pronouncements)

I can't cite chapter and verse OTTOMH, but I recall seeing an Open
Group recommendation about not using -a and -o.


--
Chris F.A. Johnson, author <http://shell.cfajohnson.com/>
===================================================================
Shell Scripting Recipes: A Problem-Solution Approach (2005, Apress)
Pro Bash Programming: Scripting the GNU/Linux Shell (2009, Apress)

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