The Most Important Tools (2/2)

file
reports the type of a file, from content (ignores the name)

od, sort, uniq, head, tail, basename, dirname
useful programs that work on file content or name
there are a huge number of them

find, xargs
look for files (by name, date, etc), turn stdin into cmdline arguments

sed, awk, perl
an higher level of data management, for gearheads

netcat
like cat, but over a network (like telnet, in a way)