Apple TV Hack: Frequently Used Unix Commands

U-M Information Technology Central Services * R1159 *November 2003

The Unix operating system supports many commands. To review a more complete definition of any of the commands listed below, type man command at the Unix shell prompt (%), where you have replaced command with the name of a Unix command. For example, type man exit to find out more about the exit command.

NOTE: This document assumes you are using Unix on the ITCS Login Service (host name login.itd.umich.edu). These instructions apply to many other Unix machines; however, you may notice different behavior if you are not using the ITCS Login Service.

TIP: The variable files refers to a list of any number of files separated by white space; in the same way; names refers to a list of file or directory names separated by white space.

NOTE: This document is also available in these formats:

General

apropos command: Locate commands by keyword lookup.
exit: Terminate your current session, or shell.
man command: Display the Unix manual page describing a given Unix command.

File System Navigation

cd: Return to your home directory.
cd directory: Change directory to make directory your current directory.
file files: Determine file type.
ls: List the contents of the current directory.
ls names: List the contents of the directories; names can name files and/or directories:
ls -l: . . . in a long format, showing permissions, owner, size, and other file info.
ls -a: . . . all files, including "hidden" files (file names that begin with a dot ".").
ls -R: . . . Recursively, for all subdirectories.
ls -t: . . . in time order (when modified, newest to oldest) rather than in name order.
pwd: Display the name of the current directory, or "print working directory."

File/Directory Manipulation

compress files: Reduces the size of a file.
uncompress files: Restores compressed files to their original form.
cp file1 file2: Copy file(s).
cp files directory: Copy file(s) into a directory.
cp -r dir1 dir2: Copy a directory and, recursively, its subdirectories.
mkdir directory: Create, or "make" a directory.
mv file1 file2: Move a file or, if file1 and file2 are in the same directory, rename a file.
mv files directory: Move files into a directory.
mv dir1 dir2: If directory dir2 exists, move dir1 into dir2; otherwise, rename dir1 as dir2.
rm files: Remove (erase) file(s).
rm -r names: Remove files, directories, and recursively, any subdirectories.
rmdir directory: Remove directory (directory must be empty).

Data Manipulation

cat files: Concatenate file(s); you can use cat to display the contents of a file (this is not advisable if the file is a binary file).
grep "pattern" files: Display all lines in the files that match a pattern.
more files: Display contents of files one screen at a time.
sort files: Order the lines in a file or files alphabetically (this command does not alter the file or files -- it merely displays the sorted output to the screen):
sort -r files: . . . in reverse order.
sort -n files: . . . numerically (puts 2 before 10 instead of after).

Networking/Communications

finger user@umich.edu: Displays information about a U-M user from the U-M Online Directory.
ssh hostname: Connect to a remote host using Secure Shell.
telnet hostname: Connect to a remote host using the telnet protocol.
talk user: Initiate a conversation with another user (end conversation with Control-C); talk works only between machines of the same architecture.

Miscellaneous

!!: Repeat last shell command.
!string: Repeat last shell command that began with string (for example, type "!m" to repeat the last command that began with "m").
cal: Display a calendar of the current month.
cal month year: Display a calendar of the given month and year. Note that the year must be fully qualified, for example, "2003" and not "03."
clear: Clears terminal screen.
date: Display the current local date and time.
who: Display a list of users currently logged in.