Simple searching using
less
Using less,
you can search though a text file for a keyword (pattern). For example,
to search through science.txt for the word science,
type
%
less science.txt
then, still in less
(i.e. don't press q to quit), type a slash followed by the word to search
/science
As you can see, less
finds and highlights the keyword. Type n to search for the next occurrence
of the word.
grep (don't ask why
it is called grep)
grep
is one of many standard UNIX utilities. It searches files for specified
words or patterns. First clear the screen, then type
%
grep science science.txt
As you can see, grep
has printed out each line containg the word science.
Or has it????
Try typing
%
grep Science science.txt
The grep command is
"case sensitive"; it distinguishes between Science and science.
To ignore upper/lower
case distinctions, use the -i
option, i.e. type
%
grep -i science science.txt
To search for a phrase
or pattern, you must enclose it in single quotes (the apostrophe symbol).
For example to search for spinning top, type
%
grep -i 'spinning top' science.txt
Some of the other options
of grep are:
-v
display those lines that do NOT match
-n precede each
maching line with the line number
-c print only the
total count of matched lines
Try some of them and
see the different results. Don't forget, you can use more than one option
at a time, for example, the number of lines without the words science or
Science is
%
grep -ivc science science.txt
wc (word count)
A handy little utility
is the wc
command, short for word count. To do a word count on science.txt,
type
%
wc -w science.txt
To find out how many
lines the file has, type
%
wc -l science.txt