Print a portion of a lines in a text file between predefined tags

Question

I have a file like the following

<g> Good wheatear </g> other parts of line 
<g> The farm land is to be sold </g> other parts of line
<g> knock knock </g> other parts of line 

I want my output to be like this:

<g> Good wheatear </g> 
<g> The farm land is to be sold </g>
<g> knock knock </g>

i.e. print the content between <g> and </g> tags including the tags

I have tried this command:

awk '/<s>/, /<\/s>/' trsTest.txt

But it prints the whole line.

How to print the content between the tags ?

Answer 1

With awk it could be:

$ awk -v FS="</?g>" '{print $2}' trsTest.txt
 Good wheatear
 The farm land is to be sold
 knock knock

Or if you want to keep the tags:

$ awk -v FS="</g> " '{print $1 FS}' trsTest.txt
<g> Good wheatear </g>
<g> The farm land is to be sold </g>
<g> knock knock </g>

Answer 2

You can simply use GNU grep and print only the matched part (-o) of the lines:

grep -o '<g>.*<\/g>' trsTest.txt

The pattern needs to be between single quotes to prevent the shell from expanding the characters (like the *)

This first command will produce:

<g> Good wheatear </g>
<g> The farm land is to be sold </g>
<g> knock knock </g>

If you don't want the tags included, then you can do this:

sed 's/.*<g>\(.*\)<\/g>.*/\1/' trsTest.txt

The ways it's working is as follows:

• match everything up to and including the opening <g> tag
• I remember the stuff in between the above using \( and \)
• match anything after the closing <\g> tag to the end of the line
• Then replace with the remembered content \1

This second command will produce:

 Good wheatear
 The farm land is to be sold
 knock knock

Answer 3

If this is XML you can use an XML parser such as xmlstarlet. (If it's HTML you can still use xmlstarlet but you have to warn it that the structure may be broken.)

I've added a bounding <root/> element to make the input legal XML:

<root>
  <g> Good wheatear </g> other parts of line
  <g> The farm land is to be sold </g> other parts of line
  <g> knock knock </g> other parts of line
</root>

And then the command to pick out the </g> elements and values is

xmlstarlet sel --template --match '//g' --copy-of '.' --nl file.xml

Output

<g> Good wheatear </g>
<g> The farm land is to be sold </g>
<g> knock knock </g>

The advantage of xmlstarlet over generic text parsing tools such as sed or grep is that it understands XML structure, so if the input file changes slightly while still remaining valid XML, xmlstarlet will still be able to parse it.

Answer 4

With awk:

awk '{if (match($0, /<g>.*<\/g>/)) 
print substr($0,RSTART,RLENGTH); }' input

In this command, built-in function match() searches for the regex.

From awk manual:

The match() function sets the predefined variable RSTART to the index. It also sets the predefined variable RLENGTH to the length in characters of the matched substring.

After finding index and length of regex in current input record($0), the built-in function substr(target,start,length) gets the expected output.

You have tried with awk '/<g>/, /<\/g>/' file. This command uses range pattern where two patterns are separated by a comma. Becasuse range pattern selects records, you are getting whole line.

Answer 5

if the tags are always the same, to include the tags, use sed

sed 's/\(.*>\).*/\1/' trsTest.txt

output is:

<g> Good wheatear </g>
<g> The farm land is to be sold </g>
<g> knock knock </g>

Updated to Quasimodo's more efficient code block

Answer 6

Using GNU sed we chop the string until the substring <g> shows up in the front.

sed -n '
 ​/^<g>/!s|<g>|\n&|;/\n/D
 ​/^<g>/s|</g>|&\n|;/\n/P
' file

---

Method using Perl:

perl -ne ' print m{(<g>.*?</g>).*(.)}s' file

python3 -c 'import sys
ifile,s1,s2 = sys.argv[1:]
with open(ifile) as fh:
 for l in fh:
   p1 = l.find(s1)
   p2 = l.find(s2,p1)
   if p1 > -1 and p2 > -1:
     print(l[p1:p2+len(s2)])
' file '<g>'  '</g>'

Answer 7

Using GNU awk:

With gensub() function (GNU awk) you can print the content between <g> and </g> tags including the tags:

awk '{print gensub(/(<g>.*<\/g>)(.*)/,"\\1","g")}' file
<g> Good wheatear </g>
<g> The farm land is to be sold </g>
<g> knock knock </g>

or not including the tags:

awk '{print gensub(/(<g>)(.*)(<\/g>)(.*)/,"\\2","g")}' file
 Good wheatear
 The farm land is to be sold
 knock knock

Answer 8

Another way with sed:

sed -n '
    s/<\/*g>/\n/g
    s/^\n/<g>/
    s/\n.*/<\/g>/
    p
' data

• Change any sequence of <g> and </g> to a new line: s/<\/*g>/\n/g
• replace the first new line with an open <g> tag: s/^\n/<g>/
• replace anything comes after the latter new line with a </g> closing tag: s/\n.*/<\/g>/
• print the line : p

---

If you'd like to remove the tag too, the sed command become:

sed -n '
    s/<\/*g>/\n/g
    s/^\n//
    s/\n.*//
    p
' data