15 sed stream editor

Question 1

sed scripts can be provided on the command line

Answer 1

sed [-e] ‘command’ files

All commands are applied in sequence to each line

Question 2

sed scripts can be provided in a separate file

Answer 2

sed -f scriptfile files

Question 3

General form of a sed command:

Answer 3

[address[,address]][!]command[arguments]

Question 4

Addresses

Answer 4

Addresses can be line numbers or regular expressions.

Question 5

Last line

Answer 5

Last line is “$”.

Question 6

Line range

Answer 6

One address selects a line, two addresses a line range (specifying start and end line).

Question 7

Optionally print

Answer 7

After this, the line is printed, unless option -n is used, in which case only the p command will print a line.

Question 8

Negate address matches

Answer 8

The ! negates address match. {. . . } can group commands per address.

Question 9

Regex enclosed in

Answer 9

Regular expressions enclosed in /. . . /. Some regular expression meta characters:

Question 10

matches any character (except new-line)

Answer 10

“.”

Question 11

matches the preceding item zero or more times

Answer 11

“*”

Question 12

matches the preceding item one or more times

Answer 12

“+”

Question 13

matches the preceding item optionally (0–1 times)

Answer 13

“?”

Question 14

matches start of line

Answer 14

“^”

Question 15

matches end of line

Answer 15

“$”

Question 16

matches one of listed characters

use in character list “^” to negate and “-” for ranges

Answer 16

“[. . . ]”

Question 17

grouping, “{n,m}” match n, . . . , m times

Answer 17

“(. . . )”

Question 18

escape following meta character

Answer 18

“\”

Question 19

Substitute all occurrences of “Windows” with “Linux” (command: s = substitute, option: g = “global” = all occurrences in line):

Answer 19

sed ‘s/Windows/Linux/g’

[used within a pipeline]

Question 20

Delete all lines that do not end with “OK” (command: d = delete):

Answer 20

sed ‘/OK$/!d’

Question 21

Print only lines between those starting with BEGIN and END, inclusive:

Answer 21

sed -n ‘/^BEGIN/,/^END/p’

Question 22

Substitute in lines 40–60 the first word starting with a capital letter with “X”:

Answer 22

sed ‘40,60s/[A-Z][a-zA-Z]*/X/’