| Linux Shell Scripting Tutorial (LSST) v1.05r3 | ||
| Chapter 6: Learning expressions with ex | ||
| | ||
Try the following command
:g/Linux/p
Linux is cooool.
Linux is now 10 years old.
Rani my sister never uses Linux
This will find only "Linux" and not the "linux", to overcome this problem try as follows
:g/[Ll]inux/p
I love linux.
My brother Vikrant also loves linux who also loves unix.
He currently learn linux.
Linux is cooool.
Linux is now 10 years old.
Next year linux will be 11 year old.
Rani my sister never uses Linux
. (DOT) is special command of linux.
Here a list of characters enclosed by [ and ], which matches any single character in that range. if the first character of list is ^, then it matches any character not in the list. In above example [Ll], will try to match L or l with rest of pattern. Let's see another example. Suppose you want to match single digit character in range you can give command as follows
:/[0123456789]
Even you can try it as follows
:g/[0-9]
Linux is now 10 years old.
Next year linux will be 11 year old.
Here range of digit is specified by giving first digit (0-zero) and last digit (1), separated by hyphen. You can try [a-z] for lowercase character, [A-Z] for uppercase character. Not just this, there are certain named classes of characters which are predefined. They are as follows:
| Predefined classes of characters | Meaning |
| [:alnum:] | Letters and Digits (A to Z or a to z or 0 to 9) |
| [:alpha:] | Letters A to Z or a to z |
| [:cntrl:] | Delete character or ordinary control character (0x7F or 0x00 to 0x1F) |
| [:digit:] | Digit (0 to 9) |
| [:graph:] | Printing character, like print, except that a space character is excluded |
| [:lower:] | Lowercase letter (a to z) |
| [:print:] | Printing character (0x20 to 0x7E) |
| [:punct:] | Punctuation character (ctrl or space) |
| [:space:] | Space, tab, carriage return, new line, vertical tab, or form feed (0x09 to 0x0D, 0x20) |
| [:upper:] | Uppercase letter (A to Z) |
| [:xdigit:] | Hexadecimal digit (0 to 9, A to F, a to f) |
For e.g. To find digit or alphabet (Upper as well as lower) you will write
:/[0-9A-Za-Z]
Instead of writing such command you could easily use predefined classes or range as follows
:/[[:alnum:]]
The . (dot) matches any single character.
For e.g. Type following command
:g/\<.o\>
She only loves to play games and nothing else.
Do you know?
This will include lo(ves), Do, no(thing) etc.
* Matches the zero or more times
For e.g. Type following command
:g/L*
Hello World.
This is vivek from Poona.
....
....
:g/Li*
Linux is cooool.
Linux is now 10 years old.
Rani my sister never uses Linux
:g/c.*and
. (DOT) is special command of linux.
Here first c character is matched, then any single character (.) followed by n number of single character (1 or 100 times even) and finally ends with and. This can found different word as follows command or catand etc.
In the regular expression metacharacters such . (DOT) or * loss their special meaning if we use as \. or \*. The backslash removes the special meaning of such meatcharacters and you can use them as ordinary characters. For e.g. If u want to search . (DOT) character at the beginning of line, then you can't use command as follows
:g/^.
Hello World.
This is vivek from Poona.
....
..
...
. (DOT) is special command of linux.
Okay! I will stop.
Instead of that use
:g/^\.
. (DOT) is special command of linux.
| Finding words | Using & as Special replacement character | |