How to handle relative folders in script

Question

Just say I have the following folder: C:\test
Inside there is one file, install.sql, and a folder 'addons' with the file three.sql
How should I run install.sql in SQL Dev?
install.sql:
@@addons/three.sql;
@@c:\test\install.sql results in:
Error starting at line 4 in command:
@@addons/three.sql
Error report:
Unable to open file: "addons/three.sql"
This is a basic example. The actual application is for install pl/json... It has the following lines in the install script:
PROMPT ------------------------------------------;
PROMPT -- Adding optional packages for PL/JSON --;
PROMPT ------------------------------------------;
@@addons/json_dyn.sql --dynamic sql execute
@@addons/jsonml.sql --jsonml (xml to json)
@@addons/json_xml.sql --json to xml copied from http://www.json.org/java/org/json/XML.java
@@addons/json_util_pkg.sql --dynamic sql from http://ora-00001.blogspot.com/2010/02/ref-cursor-to-json.html
@@addons/json_helper.sql --Set operations on JSON and JSON_LIST
But running @@C:\pljson\install.sql
-- Adding optional packages for PL/JSON --
Error starting at line 52 in command:
@@addons/json_dyn.sql --dynamic sql execute
Error report:
Unable to open file: "addons/json_dyn.sql"
Error starting at line 53 in command:
@@addons/jsonml.sql --jsonml (xml to json)
Error report:
Unable to open file: "addons/jsonml.sql"
Error starting at line 54 in command:
@@addons/json_xml.sql --json to xml copied from http://www.json.org/java/org/json/XML.java
Error report:
Unable to open file: "addons/json_xml.sql"
Error starting at line 55 in command:
@@addons/json_util_pkg.sql --dynamic sql from http://ora-00001.blogspot.com/2010/02/ref-cursor-to-json.html
Error report:
Unable to open file: "addons/json_util_pkg.sql"
Error starting at line 56 in command:
@@addons/json_helper.sql --Set operations on JSON and JSON_LIST
Error report:
Unable to open file: "addons/json_helper.sql"

Answer 1

This is SQL*Plus compatible - i.e. the expected behaviour.    Although I have to say it took me by surprise until I tested it.
As you can see from the example below,  it doesn't work in sqlplus either, unless your current directory is where install.sql is.
You can make it work in SQL Developer by setting the Select default path to look for scripts preference to the location of install.sql
C:\Documents and Settings\Administrator>sqlplus jim/xxxxx@xe
SQL*Plus: Release 11.2.0.3.0 Production on Sat Aug 17 12:28:32 2013
Copyright (c) 1982, 2011, Oracle.  All rights reserved.
Connected to:
Oracle Database 10g Express Edition Release 10.2.0.1.0 - Production
jim@XE> @q:\dev\scratch\install
SP2-0310: unable to open file "addons\test1.sql"
jim@XE> quit
Disconnected from Oracle Database 10g Express Edition Release 10.2.0.1.0 - Production
C:\Documents and Settings\Administrator>q:
Q:\>cd \dev\scratch
Q:\dev\scratch>sqlplus jim/xxxx@xe
SQL*Plus: Release 11.2.0.3.0 Production on Sat Aug 17 12:29:33 2013
Copyright (c) 1982, 2011, Oracle.  All rights reserved.
Connected to:
Oracle Database 10g Express Edition Release 10.2.0.1.0 - Production
jim@XE> @install
'TEST
test1
1 row selected.
Elapsed: 00:00:00.00
jim@XE>