Search And Replace - with Vim and Sed

Here are some examples on search and replace with Vim and Sed.

Please note that the commands starting with : are for vim and the ones starting with $ are for bash. Whatever given in () is explanation.

 
(1) Replace one pattern with another pattern in a file

:%s/windows/ubuntu/g
(replaces "windows" with "ubuntu" in current file)

$sed -e 's/windows/ubuntu/g' -i myfile
(-i makes an in-place replacement in myfile)

For case insensitive matching, use \c in vim and gI in sed.

:%s/windows\c/Ubuntu/g
(matches windows, Windows, winDows..... etc)

$sed -e 's/windows/Ubuntu/gI' -i myfile
(makes an in-place replacement in myfile)


(2) Replace with range

:3,5s/windows/ubuntu/g
(replaces in lines from 3 to 5)

:1,.s/windows/ubuntu/g
(from first line to current line[. represents current line])

:.,$s/windows/ubuntu/g 
(from current line to last line [$ represents last line])

:.,.+15s/windows/ubuntu/g
(from current line to 15 lines below)

$sed -e '10,15 s/windows/ubuntu/g' -i myfile
(replace in lines 10 to 15)

$sed -e "10,$ s/windows/ubuntu/g' -i myfile
(replaces from  10th line to last line)

$sed -e '/begin/,/end/ s/windows/ubuntu/g' -i myfile
( replacing from pattern "begin" to pattern "end")

$sed -e '/begin/,100 s/windows/ubuntu/g' -i myfile
(from pattern "begin" to line 100)

$sed -e '/begin/,+10 s/windows/ubuntu/g' -i myfile
(from pattern "begin" to 10 lines after match)


(3) Remove lines matching or not matching a pattern

:g/windows/d 
(delete all lines having pattern windows)

:10,15g/windows/d
(works with range also)

:g!/freedom/d
(delete lines not having "freedom")

 $sed -e '/windows/d' -i myfile
(deletes all lines matching pattern "windows")

$sed -e '10,15 {/windows/d}' -i myfile
(specifying range restriction)

$sed -e '/freedom/!d' -i myfile
(delete all lines without "freedom")

Here onwards, examples are mostly related to regular expressions. I will be giving examples only from Vim.


(4) Pattern at the beginning or end

Use ^ for matching patterns at the beginning of line.
Use $ for patterns at the end of line.

:%s/^windows/ubuntu/g
:%s/windows$/ubuntu/g


(5) Multiple patterns

 "|" ("OR" operator) can be used to match multiple patterns. Make sure to escape it with a "\"

:%s/windows xp\|windows 7/ubuntu/g 


(6) Patterns with wild character

 . ("dot") matches any characters except newline

:%s/a.c/pqr/g


(7) Pattern repetition

*   - zero or more
+   - one or more
{n}      - exactly matches n repeats
{n,m} - for repeats between n and m
{n,}  - for repeats at least n
{,m} - for repeats at most m

Make sure to escape "+", "{" and "}" with "\" (for both vim and sed)

:%s/px*q/pzq/g 
(matches pq, pxq, pxxq and so on)

:%s/px\+q/pzq/g
(matches pxq, pxxq, pxxxq and so on)

:%s/px\{3\}q/pzq/g 
(for exact 3 x between p and q)

:%s/px\{3,\}q/pzq/g
(for at least 3 x between p and q)


(8) Lazy matching

Usual regex syntax for lazy matching is *? (where ? makes * lazy)
But in Vim, we have to use \{-\} for lazy matching (to consider as few as possible)

(I couldn't find any lazy matching option with sed :( )

Example string:
ABC ooiiooii XYZ ooiiooii XYZ

:%s/ABC.\{-\}XYZ/PQR/g
(gives PQR ooiiooii XYZ )

:%s/ABC.*XYZ/PQR/g 
(gives PQR)


(9) Back reference

Expressions grouped with "( )" can be referenced with \1, \2 etc.
\1, \2 etc can be used in the replace string also.

:%s/\(ab\|xy\)_\1/pq/g 
(replaces "ab_ab" and "xy_xy" with "pq", leaves "ab_xy" and "xy_ab" untouched)

:%s/pq\(.*\)rs/ab\1cd/g
("pq 123 rs" will change to "ab 123 cd")


(10) Character class 

[a-z]    - matches all small letter chars
[^a-z]   - matches anything other than small letter
[a-zA-Z0-9] - will match all alphabets and numbers

:%s/(\([0-9]\+\))/[\1]/g 
(replaces all "(number)" pattern with "[number]" pattern

Some regularly used search and replaces

(a) Remove all trailing white space

:%s/\s\+$//g 
(\s- space , \+ one or more, $ - at the end)

(b) Remove ^M chars

:%s/^M//g
(Getting that ^M is bit tricky, first you need to press Ctrl-v and then press Ctrl-m)

(c) Delete blank lines

:g/^\s*$/d 
(^ - beginning of line, \s* - any number of spaces, $ - end, d - delete)

(d) Remove line numbers from the beginning

:s/^[0-9]\+\s\+//g
(^ - beginning of line, [0-9]\+ - one or more numbers, \s\+ - one or more spaces)

(e) some_file.cpp(line_no) to some_file.cpp:line_no:0

%s/\(\w\+\.cpp\)(\([0-9]\+\))/\1:\2:0/g

Notes:
[1] Be always ready to go for  :help regex or $man sed if you get stuck.
[2] Like all other posts, these aren't things I invented. I am just listing things I collected from net over a long time.