shows file space and mounted systems.
shows processes running. ps ax is a narrower form.
remove filename.
removes a directory dir and all subdirectories—careful!
lists files in the current directory and all subdirectories; I used a variant, ls -AFR > where.txt, to get a list of all the files in / and (separately) /usr before I found better ways to find files.
to change user's password (or root's password)
manual page on the UNIX® filesystem
Use find to locate filename in /usr or any of its subdirectories with
You can use * as a wildcard in "filename" (which should be in quotes). If you tell
find to search in / instead of /usr it will look for the file(s) on all mounted filesystems,
including the CDROM and the DOS partition.
An excellent book that explains UNIX commands and utilities is Abrahams & Larson, Unix for the Impatient (2nd ed., Addison-Wesley, 1996). There is also a lot of UNIX information on the Internet.