Utility Pages

ls "ListS" files. To list files in detail, the following options (among many others) are available:

ls -l  [ <filename> ]

The "-l" option provides a general "long" listing, with details on each file.

ls -Aog  [ ... ]
ls -Aogrt  [ ... ] (by reverse time)

The "Aog" option provides a similar but somewhat cleaner format than "l" and also displays files beginning with "." (but not the "." and ".." directory listings).

vi - - the "VIsual editor" - - is a simple editor with maddeningly obscure commands.

First things first: To get out of the VI editor . . .

<ESC>:q<CR>       (to quit)      
     or   
<ESC>:x<CR>       (to save and exit)    
     or   
<ESC>:quit!<CR>   (quit with no save [abandon changes])

If you absolutely must use the VI editor, then:

<ESC>     switch to command mode
i         switch back to insert-text mode (type at will: arrow keys move cursor)

About command mode:

<ESC>     switches to command mode or may be thought of as a prefix to a command.

x         delete current cursor position (without the leading colon)
p         undelete
h,j,k,l   cursor left,down,up,right

grep "Gets REgular ExPressions" - - or something like that. At it's most basic, the syntax is

grep <regular expression> <target file>

Just about any matched pair may be used as the regular expression delimieter, so all of the following are legal:

grep /some pattern/ file.file
grep 'some pattern' file.file
grep \some pattern\ file.file   

grep options begin with a dash, which can be confusing (to the program) if the pattern begins with a dash, so these also works:

grep -e some pattern file.file
grep -e some --regexp=some pattern file.file  

There are scads of options: extensive help is at grep.

chmod "CHanges MODe" of the file. Modes are if the file can execute, and who has access to it. Basically, the syntax is as follows:

chmod owner/group/others

with a summing numeric code:

0 = no access
1 = execute access
2 = write access
4 = read access 

so,

3 = write/execute access
5 = read/execute access
6 = read/write access
7 = read/write/execute access  

The numbers (1 to 7) are given for each grouping, thus

chmod 666 <filename> 

gives all categories of users read/write access

Alternatively, access may be set for all groups using single characters, r (read), w (write), and x (execute), +/- for on/off:

chmod +x <filename> --OR--
chmod -x <filename> --OR--
chmod +rw <filename> --OR--
chmod +rwx <filename> ...