STREAM EDITOR - SED

SED is a multipurpose tool which combines the work of several filters.

Ex:       sed options ‘address action’ file(s)

Addressing in sed is done in two ways:

          By one or two line nos.

          By specifying /pattern/

Line Addressing:

$ sed ‘3q’ emp.lst

Displays first 3 lines of the file and quits from sed.

$ sed –n ‘1,3p’ emp.lst

Displays first 3 lines of the file. (p and n must be used)

$ sed –n ‘$p’ emp.lst

Displays the last line of the file

$ sed –n ‘1,2p

7,9p’ emp.lst

Displays selective groups of lines

$ sed –n ‘3,$!p’ emp.lst

Do not print the lines from 3 to the end of the file.

Using Multiple Instructions:

$ sed –n –e ‘1,2p’ –e ‘7,9p’ emp.lst

Putting instructions in a file:

$ cat > patfile

1,2p

7,9p

^d

$ sed –n –f patfile emp.lst

Context Addressing:

$ sed –n ‘/director/p’ emp.lst

Displays all the lines that contain ‘director’

$ sed –n ‘/director/, /manager/p’ emp.lst

Displays all the lines from director to manager

$ sed –n ‘1, /director/p’ emp.lst

Line nos. and context addresses can be mixed

$ sed –n ‘/^a/p’ emp.lst 

Displays all the lines that start with ‘p’ (regular exp.)

Writing selected lines to a file:

$ sed –n ‘/director/w dlist’ emp.lst

$ sed –n ‘/director/w dlist

/manager/w mlist’ emp.lst

Text Editing:

Inserting            i

Appending        a

Changing          c

Deleting            d

$ sed ‘1i\

abc \

pqr’ emp.lst

$ sed ‘1a\

abc\

pqr’ emp.lst

$ sed ‘1c\

abc’ emp.lst

$ sed ‘/director/d’ emp.lst

SUBSTITUTION:

$ sed ‘s/director/director1/g’ emp.lst

$ sed ‘1,5 s/director/director1/g’ emp.lst

MULTIPLE SUBSITUTIONS:

$ sed ‘s/i/m/g

s/x/y/g’ emp.lst

$ find path –name pattern –print checks for pattern in the path and displays the file

list

$ zip xyz.zip abc pqr                             zips abc, pqr into xyz.zip

$ unzip –v xyz.zip                                  unzips a zipped file

$gzip xyz.lib                                          creates a zipped file xyz.lib.gz

$gunzip xyz.lib.gz                                  retrieves all the files

$dos2unix abc abc.unix             converts a file from dosformat to unixformat

$unix2dos abc.unix abc             converts a file from unix format to dosformat

$ at <time> <command list>                  tells unix to execute a set of commands at the given time

$ batch <commad list>              unix tells when to execute the set of commands

$ ps                                                      lists the processes along with id running on the current

                                                            terminal

$ stty                                                    sets and tells the terminal settings

$ fg                                                      brings the processes foreground

$ bg                                                     brings the processes background

$ time                                                   tells different times taken for a command to run