sed SCRIPT INPUTFILE... > OUTPUTFILE
note:if INPUTFILE==OUTPUFILE must call sed with option
note:default INPUTFILE is stdin,default OUTPUTFILE is stdout.
sed "3,5s/pattern/object/1" inputfile > outputfile:replace the first matched characters in 3-5th lines by
sed "s/pattern/object/3g" inputfile > outputfile:replace the 3-infinite matched characters in each line by