Editing Comparison of command shells (section)

=== Safe data subset ===
Scripts that invoke other scripts can be a security risk as they can potentially execute foreign code in the context of the user who launched the initial script. Scripts will usually be designed to exclusively include scripts from known safe locations; but in some instances, e.g. when offering the user a way to configure the environment or loading localized messages, the script may need to include other scripts/files.<ref>{{cite book |author-last1=Albing |author-first1=Carl |title=Bash cookbook |year=2007 |publisher=[[O'Reilly Media]] |location=Sebastopol, California, USA |isbn=978-0-596-52678-8 |edition=1st |author-last2=Vossen |author-first2=J. P. |author-last3=Newham |author-first3=Cameron |quote=[...] is hardly what one thinks of as a passive list of configured variables. It can run other commands (e.g., cat) and use if statements to vary its choices. It even ends by echoing a message. Be careful when you source something, as it's a wide open door into your script.}}</ref> One way to address this risk is for the shell to offer a safe subset of commands which can be executed by an included script.