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Full Discussion: Assigning Variables
Top Forums Shell Programming and Scripting Assigning Variables Post 302891115 by Scrutinizer on Tuesday 4th of March 2014 02:42:08 AM
Old 03-04-2014
The first means:
Quote:
${parameter-[word]}
Use Default Values. If parameter is unset, the expansion of word is substituted. Otherwise, the value of parameter is substituted.
The second is a regular variable assignment. The quotes are not necessary:

Both variables are exported.

To give an example:
Code:
$ echo "$var"

$ var=${var-foo}
$ echo "$var"
foo
$ var=
$ var=${var-foo}
$ echo "$var"

$ unset var
$ echo "$var"

$ var=${var-foo}
$ echo "$var"
foo


Last edited by Scrutinizer; 03-04-2014 at 04:00 AM..
This User Gave Thanks to Scrutinizer For This Post:
 

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APC_ADD(3)								 1								APC_ADD(3)

apc_add - Cache a new variable in the data store

SYNOPSIS
bool apc_add (string $key, mixed $var, [int $ttl]) DESCRIPTION
array apc_add (array $values, [mixed $unused = NULL], [int $ttl]) Caches a variable in the data store, only if it's not already stored. Note Unlike many other mechanisms in PHP, variables stored using apc_add(3) will persist between requests (until the value is removed from the cache). PARAMETERS
o $key - Store the variable using this name. $keys are cache-unique, so attempting to use apc_add(3) to store data with a key that already exists will not overwrite the existing data, and will instead return FALSE. (This is the only difference between apc_add(3) and apc_store(3).) o $var - The variable to store o $ttl - Time To Live; store $var in the cache for $ttl seconds. After the $ttl has passed, the stored variable will be expunged from the cache (on the next request). If no $ttl is supplied (or if the $ttl is 0), the value will persist until it is removed from the cache manually, or otherwise fails to exist in the cache (clear, restart, etc.). o $values - Names in key, variables in value. RETURN VALUES
Returns TRUE if something has effectively been added into the cache, FALSE otherwise. Second syntax returns array with error keys. EXAMPLES
Example #1 A apc_add(3) example <?php $bar = 'BAR'; apc_add('foo', $bar); var_dump(apc_fetch('foo')); echo " "; $bar = 'NEVER GETS SET'; apc_add('foo', $bar); var_dump(apc_fetch('foo')); echo " "; ?> The above example will output: string(3) "BAR" string(3) "BAR" SEE ALSO
apc_store(3), apc_fetch(3), apc_delete(3). PHP Documentation Group APC_ADD(3)
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