Linux Command Line Odds and Ends

Here are some useful Odds and Ends... most are related to command line stuff, some not; whatever, enjoy. Most of these came from either scouring the web, or Learning the Bash Shell or Learning Red Hat Enterprise Linux and Fedora.

Job Control

• kill %<PID> kill a process
• kill -QUIT %<PID> kill a process, a bit stronger
• kill -KILL %<PID> unconditionally kill a process
• fg bring a background job into the foreground
• jobs list jobs running
• ps process information

File permissions (owner, group, others)

• 0 ---
• 1 --x
• 2 -w-
• 3 -wx
• 4 r--
• 5 r-x
• 6 rw-
• 7 rwx

Globbing

• * matches zero or more characters
• ? matches any one character
• [abc...] matches any of the characters specified
• [a-z] matches any character in the specified range
• [!abc...] matches any character other than those specified
• [!a-z] matches any character not in the specified range
• ~ home directory of current user
• ~userid home directory of a user
• ~+ current working directory
• ~- previous working directory

Quotes

• 'xxx' interprereted literally, variables not substituted
• "xxx" interprereted literally, variables ARE substituted
• `xxx` output of xxx command replaces it

Command line special characters

• # comment
• ; command seperator
• & run in background
• \ command continued on next line
• | pipe

Input/Output Redirectors

• prog > file stdout to file
• prog 2> file stderr to file
• prog >> file concatenates stdout to file
• prog 2>> file concatenates stderr to file
• prog > file 2>&1 stdout and stderr to file
• prog >> file 2>&1 concatenates stdout and stderr to file
• prog < file stdin from file
• prog << text reads stdin until a line matching text is found, then EOF posted ("here document")
• prog | prog2 pipe stdout
• prog 2>&1 | prog2 pipe stdout and stderr
  

Command Line Movement

• Ctrl+Shift+N open new console window
• Crtl+Alt+F[1-7] go to virtual console 1-6 or X(7)
• Ctrl+Alt+Backspace stop X and go to console
• Alt+B Back one word
• Alt+F Forward one word
• Ctrl+A Beginning of line
• Ctrl+E End of line
• Alt+D Delete word |------------->X
• Ctrl+D Delete char
• Ctrl+K Delete |------------->X
• Ctrl+U Delete X<-----------|
• Ctrl+L Clear screen
• Ctrl+Y UNDO
• ESC+. Insert last word of previous command
• TAB Possible completions

IRC

• /server join a server
• /join join a channel
• /quit quit the server
• /close close the current screen
• /part leave the current channel
• /partall leave all channels
• /msg msg a user with a new window
• /notice msg a user without a new window
• /query force a window open to msg a user
• /chat DCC with a user
• /dns dns lookup for a user
• /ping ping a user
• /me *** does something
• /whois query whois for a user

Ctrl Keys

• Ctrl+C intr: stop current command
• Ctrl+D eof: end of input
• Ctrl+\ quit: stop current command (if Ctrl+C doesn't work)
• Ctrl+S stop: halt output to screen
• Ctrl+Q resume output to screen
• Ctrl+Z suspend current command (works well with bg, fg and jobs)
  

Escape Sequences

• \a alert (bell)
• \b backspace
• \c omit final newline
• \E escape character
• \f formfeed
• \n newline
• \r return
• \t tab
• \v vertical tab
• \xxx ASCII in octal
• \\ backslash

Tar: tarball options

• -c create
• -r append
• -t list contents
• -x extract
• -a append files
• -v verbose
• -z zip/unzip
• -f use filename
• Oft-used:
• tar -cf foo.tar foo; gzip foo.tar
• gunzip bar.tar.gz; tar -xvf bar.tar