5 * **`.`** (a single period) --> refers to the current directory
6 * **`..`** (a double period) --> refers to the directory above the current directory
7 * **`~`** --> refers to your home directory. _Note:_ this command does NOT work on Windows machines (Mac and Linux are okay)
8 * **`*`** --> wildcard (multiple characters). `*.txt` will match all files in the current directory that end with `.txt`
9 * **`?`** --> wildcard (single character). `?.txt` will match `a.txt` and `b.txt`, but not `ab.txt`
10 * **`cd ./dirname`** --> changes the current directory to the directory `dirname`
11 * **`ls -F`** --> tells you what files and directories are in the current directory
15 ## 2. Creating Things:
16 ### a) How to create new files and directories...
17 * **`mkdir ./dirname`** --> makes a new directory called dirname below the current directory. _Note:_ Windows users will need to use `\` instead of `/` for the path separator
18 * **`nano filename`** --> if `filename` does not exist, `nano` creates it and opens the `nano` text editor. If the file exists, `nano` opens it. _Note:_ _(i)_ You can use a different text editor if you like. In gnome Linux, `gedit` works really well too. _(ii)_ `nano` (or `gedit`) create text files. It doesn't matter what the file extension is (or if there is one)
20 ### b) How to delete files and directories...
21 #### _Remember that deleting is forever. There is NO going back_
22 * **`rm ./filename`** --> deletes a file called `filename` from the current directory
23 * **`rmdir ./dirname`** --> deletes the directory `dirname` from the current directory. _Note:_ `dirname` must be empty for `rmdir` to run.
25 ### c) How to copy and rename files and directories...
26 * **`mv tmp/filename .`** --> moves the file `filename` from the directory `tmp` to the current directory. _Note:_ _(i)_ the original `filename` in `tmp` is deleted. _(ii)_ `mv` can also be used to rename files (e.g., `mv filename newname`
27 * **`cp tmp/filename .`** --> copies the file `filename` from the directory `tmp` to the current directory. _Note:_ _(i)_ the original file is still there
31 ## 3. Pipes and Filters
32 ### a) How to use wildcards to match filenames...
33 ### b) That wildcards are expanded by the shell before commands are run...
34 ### c) How to redirect a command's output to a file...
35 ### d) How to redirect a command's input from a file...
36 ### e) How to use the output of one command as the input to another with a pipe...
37 ### f) That combining single-purpose filters with pipes is the most productive way to use the shell...
38 ### g) That if a program conforms to Unix conventions, it can easily be combined with others...
47 * **`varname[0]`** --> _Note:_ the shell is zero indexed. That means you always start counting from zero
51 * **`${varname[@]` -->
56 NEED TO DO VARIABLE ASSIGNMENT FIRST!!!!
57 ### a) How to repeat operations using a loop...
59 `for filename in *.dat
61 mv ${filename} ${newname}
71 ### b) That the loop variable takes on a different value each time through the loop...
72 ### c) The difference between a variable's name and its value...
73 ### d) Why spaces and some punctuation characters shouldn't be used in files' names...
74 ### e) How to display history and re-use commands...
75 * **`history`** --> displays your command history to the standard output (usually the screen)
80 ### a) How to store shell commands in a file...
81 ### b) How to run a shell script...
82 ### c) How to pass filenames into a shell script...
87 ### a) How to select lines matching patterns in text files...
88 * **`grep [options] day haiku.txt`** --> finds every instance of the string `day` in the file haiku.txt and pipes it to standard output.
89 * **`-E`** --> tells grep you will be using a regular expression. Enclose the regular expression in quotes. _Note:_ the power of `grep` comes from using regular expressions. Please see the regular expressions sheet for examples
90 * **`-i`** --> makes matching case-insensitive
91 * **`-n`** --> limits the number of lines that match to the first n matches
92 * **`-v`** --> shows lines that do not match the pattern (inverts the match)
93 * **`-w`** --> outputs instances where the pattern is a whole word
95 ### b) How to find files with certain properties...
96 * **`find . -type d` -->
97 * **`-type [df]`** --> d lists directories; f lists files
98 * **`-maxdepth n`** --> `find` automatically searches subdirectories. If you don't want that, specify the number of levels below the working directory you would like to search
99 * **`-mindepth n`** --> starts `find`'s search n levels below the working directory
101 ### c) How to use one command's output as arguments to another command...
103 ### d) How are text and binary files different?...