In case you need to save an output from SAP GUI into PDF format there are couple of options.
First of all Spool functionality supports saving PDFs within t=codes related to spool request such as SP02. It is available under menu Spool requests -> Forward -> Export as PDF…
In case system is based on older versions of SAP NetWeaver there are couple of ABAP reports that can be used to convert any spool request to PDF such as: RSTXPDFT4.
At last there are few applications t-codes such as in SD module: VF03 (Display Invoice) in which by entering PDF! Into t-code field automatically generates the PDF file.
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