Useful Linux Commands

ident    - Display ident strings in a binary 
lastlog  - Display all users who have and haven't logged in 
ldd      - Display shared library requirements of a program 
lsof     - List open files 
strip    - Strip extraneous symbols from binaries 
valgrind - Check programs for memory leaks, etc.
 
make an archive - find xxx | cpio -oBc -O archive.name 
read an archive - cpio -iBdu -I archive.name 
dir  an archive - cpio -itv < archive.name 
 
xcopy like functionality: 
  find . -type f -name \*pat\* | cpio -pdmu  

valgrind:
  valgrind --leak-check=full [--track-origins=yes] <program> <args>

Backing up with tar through SSH:
  tar -jcf - /mnt/gentoo | ssh user@address "cat >backup.tbz2"

Get all the files in a given directory with a given extension without recursion:
  wget -np --mirror --progress=bar -nH --cut-dirs=5 -erobots=off --reject="index.html*" -A.xz http://core.ring.gr.jp/pub/text/TeX/ptex-win32/current/