What is the Tomcat/temp directory in Tomcat 7?

Question

A fresh download of Tomcat 7 (I'm using 7.0.19) contains a 'temp' directory containing the single file, 'safeToDelete.tmp'. What is this directory used for by Tomcat or how is should be used by Tomcat users (developers)?

Answer 1

When you startup Tomcat, using startup.bat (Windows) or startup.sh, it calls catalina.bat/catalina.sh respectively.

Catalina then needs a temp directory to be set. It does this by setting the CATALINA_TMPDIR variable to TOMCAT_HOME\temp folder and assigns it to java system environment variable as java.io.tmpdir.

This is copied from catalina.bat:

rem   CATALINA_TMPDIR (Optional) Directory path location of temporary directory
rem                   the JVM should use (java.io.tmpdir).  Defaults to
rem                   %CATALINA_BASE%\temp.

Where CATALINA_BASE is TOMCAT_HOME (if run using the startup script).

We carry on:

if not "%CATALINA_TMPDIR%" == "" goto gotTmpdir
set "CATALINA_TMPDIR=%CATALINA_BASE%\temp"

Finally:

if not "%SECURITY_POLICY_FILE%" == "" goto doSecurity
%_EXECJAVA% %JAVA_OPTS% %CATALINA_OPTS% %DEBUG_OPTS% -Djava.endorsed.dirs="%JAVA_ENDORSED_DIRS%" -classpath "%CLASSPATH%" -Dcatalina.base="%CATALINA_BASE%" -Dcatalina.home="%CATALINA_HOME%" -Djava.io.tmpdir="%CATALINA_TMPDIR%" %MAINCLASS% %CMD_LINE_ARGS% %ACTION%
goto end
:doSecurity
%_EXECJAVA% %JAVA_OPTS% %CATALINA_OPTS% %DEBUG_OPTS% -Djava.endorsed.dirs="%JAVA_ENDORSED_DIRS%" -classpath "%CLASSPATH%" -Djava.security.manager -Djava.security.policy=="%SECURITY_POLICY_FILE%" -Dcatalina.base="%CATALINA_BASE%" -Dcatalina.home="%CATALINA_HOME%" -Djava.io.tmpdir="%CATALINA_TMPDIR%" %MAINCLASS% %CMD_LINE_ARGS% %ACTION%
goto end

Finally, the java.io.tmpdir is pointed to the CATALINA_TMPDIR where the JVM write temporary files including disk-based storage policies.