Replacing string in file Unix - linux

I have a text file file1.txt on Unix. I'd like to produce another file file2.txt, in which I replace all occurrences of apple-pie with apple_pie. What command can I use?


Use sed to do a global substitution on file1.txt and redirect the output to file2.txt:
sed 's/apple-pie/apple_pie/g' file1.txt > file2.txt


sed has better performance than awk but both will work for this search and replace. Reference
If you put the commands in a script (e.g., ksh, sh) then here is the syntax:
awk '{gsub(/apple-pie/,"apple_pie");print}' "file1.txt" > "file2.txt"
sed -e 's/apple-pie/apple_pie/g' "file1.txt" > "file2.txt"

Related

i want add 3 line with sed or awk command in file config.xml

I have a linux centos 7 server and i want Below lines to file with name config.xml using sed command
<vhostMap>
<vhost>google</vhost>
<domain>google.com, www.google.com</domain>
</vhostMap>
i want add this lines after line 10 at config.xml file
i want add this with a command at centos7, its possible?
i have searched and i saw this is possible with sed or awk command
how i can do this with sed or awk command?

GNU sed:
sed '10a <vhostMap>\n <vhost>google</vhost>\n <domain>google.com,www.google.com</domain>\n</vhostMap>' config.xml

Almost the same with awk:
awk '{ print $0 ; if(NR == 10) printf "<vhostMap>\n <vhost>google</vhost>\n <domain>google.com, www.google.com</domain>\n</vhostMap>\n" }' config.xml

This might work for you (GNU sed and shell):
cat <<\! | sed '10r /dev/stdin' file
<vhostMap>
<vhost>google</vhost>
<domain>google.com, www.google.com</domain>
</vhostMap>
!
Place the lines to be appended in a here-doc and append them after line 10 of the file by reading them in as stdin via a pipe.

How to replace one or more consecutive symbols with one symbol in shell

I have a file containing consecutive symbols (as pipe "|") like
ANKRD54,LIAR,allergy,|||
ANKRD54,LIAR,asthma,||20447076||
ANKRD54,LIAR,autism,||||
ANKRD54,LIAR,cancer,|||
ANKRD54,LIAR,chronic_obstructive_pulmonary_disease,|||
ANKRD54,LIAR,dental_caries,||||
Now using shell or a sed command in shell is it possible to replace multiple pipe with one pipe like
ANKRD54,LIAR,allergy,|
ANKRD54,LIAR,asthma,|20447076|
ANKRD54,LIAR,autism,|
ANKRD54,LIAR,cancer,|
ANKRD54,LIAR,chronic_obstructive_pulmonary_disease,|
ANKRD54,LIAR,dental_caries,|

I guess the easiest way is use built-in commands: cat your_file | tr -s '|'

Pass your text to sed (e.g. via a pipe)
cat your_file | sed "s/|\+/|/g"

You can do that with a simple awk gsub as:-
awk -F"," -v OFS="," '{gsub(/[|]+/,"|",$4)}1' file
See it in action:-
$ cat file
ANKRD54,LIAR,allergy,|||
ANKRD54,LIAR,asthma,||20447076||
ANKRD54,LIAR,autism,||||
ANKRD54,LIAR,cancer,|||
ANKRD54,LIAR,chronic_obstructive_pulmonary_disease,|||
ANKRD54,LIAR,dental_caries,||||
$ awk -F"," -v OFS="," '{gsub(/[|]+/,"|",$4)}1' file
NKRD54,LIAR,allergy,|
ANKRD54,LIAR,asthma,|20447076|
ANKRD54,LIAR,autism,|
ANKRD54,LIAR,cancer,|
ANKRD54,LIAR,chronic_obstructive_pulmonary_disease,|
ANKRD54,LIAR,dental_caries,|

files comparison in linux using line numbers

I am looking to compare file1.txt contents with the last n file contents of file2.txt Can someone help in identifying this logic using anything in shell script.
Example if file1.txt has 10 lines, the last 10 lines of file2.txt should be compared for difference.

With bash's process substitution <() and command substitution $().
diff file1.txt <(tail -n $(wc -l < file1.txt) file2.txt)

How to remove lines from text file not starting with certain characters (sed or grep)

How do I delete all lines in a text file which do not start with the characters #, & or *? I'm looking for a solution using sed or grep.

Deleting lines:
With grep
From http://lowfatlinux.com/linux-grep.html :
The grep command selects and prints lines from a file (or a bunch of files) that match a pattern.
I think you can do something like this:
grep -v '^[\#\&\*]' yourFile.txt > output.txt
You can also use sed to do the same thing (check http://lowfatlinux.com/linux-sed.html ):
sed '^[\#\&\*]/d' yourFile.txt > output.txt
It's up to you to decide
Filtering lines:
My mistake, I understood you wanted to delete the lines. But if you want to "delete" all other lines (or filter the lines starting with the specified characters), then grep is the way to go:
grep '^[\#\&\*]' yourFile.txt > output.txt

sed -n '/^[#&*].*/p' input.txt > output.txt
this should work.
sed -ni '/^[#&*].*/p' input.txt
this one will edit the input file directly, be careful +

egrep '^(&|#|\*)' input.txt > output.txt

sed extract text between two patterns where second pattern may be either of one

I am trying to extract text between pattern1 (fixed) and pattern2 (this can be p2-1/p2-2).
can you please tell me how to achieve this in a single command?
A file starts with start and ends with either end or close
File1:
======
junktest
data
start
stackoverflow
sed
close
File2:
======
data2
start
stackoverflow
end
I can extract text from File1 with
sed -n "/start/,/close/p"
And from File2 with
sed -n "/start/,/end/p"
I need a single sed command to achieve both..
something like:
sed -n "/start/, /close or end /p"

Both GNU sed and BSD sed:
sed -nE '/start/,/close|end/p' file

This awk looks better
awk '/start/,/end|close/' file

sed -n -E "/Word1/,/Word2-1/p" | sed -n -E "/Word1/,/Word2-2/p"

Easy with awk:
$ awk '/start/{p=1}p{print}/end|close/{p=0}' file

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