for i in `ls -1 | grep -v <filetokeep>`; do rm -rf $i; done

• to generate a .s: gcc -S -c foo.c
• to output combined C and assembly: gcc -c -g -Wa,-a,-ad foo.c > foo.lst
• to assemble a .s: as -o foo.o foo.s. Use -gstabs for debug and -a to print memory listing.
• to assemble a .o: gcc foo.o -o foo

To reload .emacs: M-x load-file ~/.emacs

tar -xvf <thetar.tar> <thefile>

tar -xvf <thetar.tar> -C <thedir>

More exactly, it'll convert from “AA BB CC” to “0xAA, 0xBB, 0xCC” with each line having 8 bytes.

hexdump -v -e '8/1 "0x%02x, "' -e '"\n"' <filetodump>

Take a screenshot

$ xwd -root -out scrdump

View a screenshot

$ xwud -in scrdump