Thursday, December 23, 2010

Linux-basics


Character
Description
\
Escape character. If you want to reference a special character, you must “escape” it with a backslash first.
Example: touch /tmp/filename\*
/
Directory separator, used to separate a string of directory names.
Example: /usr/src/linux
.
Current directory. Can also “hide” files when it is the first character in a filename.
..
Parent directory
~
User's home directory
*
Represents 0 or more characters in a filename, or by itself, all files in a directory.
Example: pic*2002 can represent the files pic2002, picJanuary2002,picFeb292002, etc.
?
Represents a single character in a filename.
Example: hello?.txt can represent hello1.txt, helloz.txt, but not hello22.txt
[ ]
Can be used to represent a range of values, e.g. [0-9], [A-Z], etc.
Example: hello[0-2].txt represents the names hello0.txt,hello1.txt, and hello2.txt
|
Pipe”. Redirect the output of one command into another command.
Example: ls | more
>
Redirect output of a command into a new file. If the file already exists, over-write it.
Example: ls > myfiles.txt
>>
Redirect the output of a command onto the end of an existing file.
Example: echo .Mary 555-1234. >> phonenumbers.txt
<
Redirect a file as input to a program.
Example: more < phonenumbers.txt
;
Command separator. Allows you to execute multiple commands on a single line.
Example: cd /var/log ; less messages
&&
Command separator as above, but only runs the second command if the first one
finished without errors.
Example: cd /var/logs && less messages
&
Execute a command in the background, and immediately get your shell back.
Example: find / -name core > /tmp/corefiles.txt &

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