Command Line Crib Sheet
From LMU BioDB 2013
Commands, Special Symbols, and Keyboard Shortcuts
| ! | exclamation point/bang | Shortcut for repeating a command—!<command number> repeats the command with that number (as listed by the history command); !! repeats the last command |
| / | forward slash | Separates successive folders in a cd command |
| ~, ~username | tilde | Shortcut for a user’s home folder; when immediately followed by a username (no spaces), this represents that user’s home folder |
| cd <directory or folder> | change directory | Changes the current directory/folder to the one indicated in the command |
| Ctrl-C | “Panic” key—bail out of the current program and jump back to the command line | |
| Ctrl-D | “End input” key—ends a program when using it in “practice” mode (where you type the data that you want it to manipulate) | |
| exit | exit | Log out of your command line session. |
| history | history | Lists the commands you have typed so far |
| left/right arrow keys | Go backward/forward across current command (allowing you to edit it) | |
| logout | logout | Log out of your command line session. |
| pwd | print working directory | Displays the directory/folder in which you are working; the command prompt also shows this |
| Tab key | autocomplete | Lists possible matching choices if there is more than one, or autofills immediately if there is only one match |
| up/down arrow keys | Go back and forth through command history |
Search Pattern Symbols (a.k.a. regular expression or regex symbols)
Used by grep, sed, and XMLPipeDB Match to indicate what patterns to find.
| . | Single-character wildcard | Matches any character |
| * | Zero or more | Matches zero or more of the symbol that precedes it |
| ^ | Beginning of line | Matches the pattern after it only if it appears at the beginning of a line |
| $ | End of line | Matches the pattern before it only if it appears at the end of a line |
| + | One or more | Matches one or more of the symbol that precedes it |
| \" | Double-quote character | Matches a double-quote in a line; the extra backslash (\) is needed so that this quote is not confused for indicating the end of the search pattern |
| \d | Number 0-9 (i.e., digit) | Matches any single-digit number |
| \w | Letter or number (i.e., something that would appear in a word) | Matches any letter or number, but not punctuation, spaces, or other symbols |
sed Search/Replace Directives
To be written.
