cd
  – Change directory. This lets
you navigate to different directories (folders).

Examples:

cd Documents

go into a subdirectory (of the current
directory) named “Documents”

cd Documents/temp

go into “Documents”, then from
there into a subdirectory named “temp”

cd ..

go up to the parent of the current directory

cd ../..

go up two levels, to the parent’s parent

cd /

go to the top of the boot volume

cd /Users

go to the top of the boot volume, then into the
top-level directory named “Users”

cd ~

go to your home directory (note: that’s a tilde, not
a dash)

cd ~/Documents

go to your home directory, then into
your “Documents” directory

cd '/Applications (MacOS 9)'

go to the of the boot
volume, then into the top-level directory named “Applications (MacOS 9)”.
The quote marks tell the shell (command interpreter) to ignore the special
characters (spaces and parentheses) in the directory name that would
otherwise confuse it.

cd -

go back to the previous directory

pwd
  – Print working
directory. This prints the path of the current working
directory (i.e. it tells you where you are).

ls
  – List the files in the current
directory, and (optionally) their characteristics.

Examples:

ls

list just the names of the files in the current directory

ls -l

(long) list the files with their
characteristics (size, privs, owner, etc)

ls -lo

list the files with their flags (see
chflags) in addition to the
usual characteristics -l shows

ls -a

list all files in the
current directory (including those that would normally be invisible)

ls -F

list filenames with a special character at the end that
tells you what kind of file it is (“/” for directory, “*” for unix executable,
“@” for alias/symlink, etc)

ls *.jpg

list the names of all files with names ending in “.jpg”

ls a*

list the names of all files with names beginning with “a”

ls *att*

list the names of all files with names containing “att”