Use o argumento "-o". por exemplo. pdfdetach -saveall JSPopupCalendar.pdf -o /subfolder
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-saveall
Save all of the embedded files. This uses the file names associated with the embedded files (as printed by the "-list" switch). By default, the files are saved in the current directory; this can be changed with the "-o" switch.
-o path
Set the file name used when saving an embedded file with the "-save" switch, or the directory used by "-saveall".
Exemplo, mostrando como desanexamos o arquivo KSBASE.WQ2 de dentro de fileAttachment.pdf.
$ pdfdetach -saveall fileAttachment.pdf -o bar
$ find . -ls
384329 0 drwxrwxr-x 3 steve steve 43 Sep 7 17:42 .
9137752 0 drwxrwxr-x 2 steve steve 24 Sep 7 17:42 ./bar
8544834 24 -rw-rw-r-- 1 steve steve 20668 Sep 7 17:42 ./bar/KSBASE.WQ2
384331 80 -rw-rw-r-- 1 steve steve 78950 Nov 2 2017 ./fileAttachment.pdf
$