sed -n '1p' fileName
sed -n '1p;3p' fileName
sed -n '1,3p' fileName
sed -i '1d' fileName
sed -i '1d;3d' fileName
sed -i '1,3d' fileName
sed '1d' fileName >tmpfile && mv tmpfile fileName
sed -i '/^abc/,$d' fileName
sed -i '/abc/d' filename
sed -i '262,265s/x/y/' filename
sed -i '262,255s|x|y' filename
sed "/old content/c\new content/" filename sed "s/old content/new content/" filename