sed Samples

Quick Examples:

General Syntax:
sed -option 'general expression' [data-file]
sed -option sed-script-file [data-file]

Option can be:

Option	Meaning	Example
-e	Read the different sed command from command line.	$ sed -e 'sed-commands' data-file-name $ sed -e 's/test/TEST/' File $ sed -e
-f	Read the sed command from sed script file.	$sed -f $ sed -f chgdb.sed friends.tdb
-n	Suppress the output of sed command. When -n is used you must use p command of print flag to explicitly specify what is to be printed.	$ sed -n '/^\*..$/p'

Search and replace:

$ sed 's/Linux/UNIX/' TestFile > file.out

here 's' is the search command and '/' is the delimiter used to separate the text to be searched and replaced.

Deleting blank lines

Using sed you can delete all blank line from file as follow
$ sed '/^$/d' demofile1
Here the pattern /^$/, match blank line and d, command deletes the blank line.

Using Regular Expressions with sed

$ sed -n '/10\{2\}1/p' TestFile

prints 1001, search pattern \{2\}.
Syntax:
\{n,\}
At least nth occurrences will be matched. So /10\{2\} will look for 1 followed by 0 (zero) and \{2\}, tells sed look for 0 (zero) for twice.

Matching any number of occurrence

Syntax:
\{n,\m}
Matches any number of occurrence between n and m.

Example:
$ sed -n '/10\{2,4\}1/p' TestFile2
1001
10001
100001
Will match "1001", "10001", "100001" but not "101" or "10000000".

$ sed -n '/^\*..$/p' demofile2
***
***
Above command prints all lines that begins with *** (three stars or asterisks),

Explanation:

Command

Explanation
^	Beginning of line
\*	Find the asterisk or star (\ remove the special meaning of '*' metacharacter)
..	Followed by any two character (you can also use \*\* i.e. $ sed -n '/^\*\*\*$/p' demofile2 )
$	End of line (So that only three star or asterisk will be matched)
/p	Print the pattern.

Also the following expression can be used for the same purpose
$ sed -n '/^\*\{2,3\}$/p' TestFile2

Following command finds out lines between *** and *** and then delete all those line
$sed -e '/^\*\{2,3\}$/,/^\*\{2,3\}$/d' demofile2 > /tmp/fi.$$
$cat /tmp/fi.$$

Above expression can be explained as follows

Expression	Meaning
^	Beginning of line
\*	Find the asterisk or star (\ remove the special meaning of '*' metacharacter)
\{2,3\}	Find next two asterisk
$	End of line
,	Next range or search pattern
^\*\{2,3\}$	Same as above
d	Now delete all lines between *** and *** range