sed with multiple expression for in-place argument

Depending on the version of sed on your system you may be able to do

sed -i 's/Some/any/; s/item/stuff/' file

You don't need the g after the final slash in the s command here, since you're only doing one replacement per line.

Alternatively:

sed -i -e 's/Some/any/' -e 's/item/stuff/' file

Or:

sed -i '
  s/Some/any/
  s/item/stuff/' file

The -i option (a GNU extension now supported by a few other implementations though some need -i '' instead) tells sed to edit files in place; if there are characters immediately after the -i then sed makes a backup of the original file and uses those characters as the backup file's extension. Eg,

sed -i.bak 's/Some/any/; s/item/stuff/' file

or

sed -i'.bak' 's/Some/any/; s/item/stuff/' file

will modify file, saving the original to file.bak.

Of course, on a Unix (or Unix-like) system, we normally use '~' rather than '.bak', so

sed -i~ 's/Some/any/;s/item/stuff/' file

You can chain sed expressions together with ";"

%sed -i 's/Some/any/g;s/item/stuff/g' file1
%cat file1
anything  123 stuff1
anything  456 stuff2
anything  768 stuff3
anything  353 stuff4

Multiple expression using multiple -e options:

sed -i.bk -e 's/Some/any/g' -e 's/item/stuff/g' file

or you can use just one:

sed -i.bk -e 's/Some/any/g;s/item/stuff/g' file

You should give an extension for backup file, since when some implementation of sed, like OSX sed does not work with empty extension (You must use sed -i '' to override the original files).