Replace whole line using sed or awk

[Ross W]

Hi,

I need to replace an entire line that contains a certain string with another line.

Does anyone know how I could do this? If awk or sed are not the best tools to do this I am open to suggestions.

Sorry if I am duplicating, but I have been reading man pages and trawling the posts on this website for the last 2 hours.

Cheers
Ross

[Michael Tully]

Is this what you after?

$ sed 's /string/new string/g' old_filename >new_filename

[Con O'Kelly]

Hi Ross

Don't know if this is what you're after:

sed 's///' > /tmp/newfile.

Then mv the newfile over the old.

Cheers
Con

[RAC_1]

sed 's/string/new string/g' file > new_file

[Ross W]

Very similar, but I need the whole line replaced, not just the search string text.

For Example:
I have a file which sometimes contains this text.

quick brown fox

and sometimes contains

slow brown fox

I want to search for "brown" and then replace the entire line.

Any ideas?

Thanks
Ross

[twang]

Have a look at this thread, it may helps:

https://community.hpe.com/t5/System-Administration/bd-p/itrc-156#.WNOdhE27odk

[john korterman · Accepted solution]

Hi,
the slow approach:

#!/usr/bin/sh
while read LINE
do
echo "$LINE" | grep -iq brown
if [ "$?" = "0" ]
then
echo "Replaced line"
else
echo "$LINE"
fi
done <$1


regards,
John K.

[Ionut Grigorescu_2]

awk '{x=0;for(i=1;i<=NF;i++){if($i ~ /brown/) print "new line/string";x=1;break}};if (x==0) print $0}' your_file > new_file

[Caesar_3]

Hello!

Script on perl:

#!/usr/bin/perl
open (FD, "SRC_FILENAME");
open (FDN, ">TRGET_FILENAME");

foreach ()
{
if (/STRING_FOR_REPLACE/)
{
print FDN "NEW_STRING_LINE";
}
else
{
print FDN "$_";
}
}

close (FDN);
close (FD);
#END

Caesar

[Rolf Modin]

awk ' toupper($0) ~ /BROWN/ {print "new row"}'

I should think this would do what I expect You to ask for.

If brown exist anyware in the input row, case independent, the whole input line is replaced by a new standard row.

[Rolf Modin]

Hm...

awk ' toupper($0) ~ / BROWN[\.,!? ]/ {print "new row"}' input > output

This version acts only when 'brown' is used as a sepatate word, and not for instnace as 'brownies'. It accepts ".", ",", "!", "?" and " " as the character after 'brown'.

[Stephen Day]

A nice simple approach:

Say the string you are looking for is STRING_TO_BE_REPLACED.
And the line you want to insert is LINE_TO_REPLACE_WITH.
The input file is 'file', the output file is 'new_file':

cat file | sed 's/^.*STRING_TO_BE_REPLACED.*$/LINE_TO_REPLACE_WITH/' >new_file

The ^ is a start of line anchor, the '.*' is a wildcard, the $ is a end of line anchor.

Personally I think this looks a lot cleaner than most of the other ways to do this I've seen here.

[Rolf Modin]

shame on me!

This is how it works well:

awk '{if(toupper($0) ~ / BROWN[;\.,!? ]/) {print "new row"} else {print $0}}' input


The text "brown" will trigger a complete different standard line to be printed instead of the line "brown" is found in. But the line will only be replaces if "brown" begins with a space, and if the character after "brown" is one of ";.,!?" or space. The check will ignore case.

If it looks like "[" or "]" that should be replaces with sqare brackets instead.

[Rolf Modin]

shame on me!

This is how it works well:

awk '{if(toupper($0) ~ / BROWN[;\.,!? ]/) {print "new row"} else {print $0}}' input


The text "brown" will trigger a complete different standard line to be printed instead of the line "brown" is found in. But the line will only be replaced if "brown" begins with a space, and if the character after "brown" is one of ";.,!?" or space. The check will ignore case.

If it looks like "[" or "]" that should be replaces with sqare brackets instead.

[Robert Salter]

You could put it in a script if you have to do this more than once using a couple of different variables i.e;

# file1 contains line to insert
REPLN=`cat file1`
# or set the variable with the line to be #inserted
REPLN="dumb ol fox"

sed "s/^.*$2.*$/$REPLN/ $1 > $1.a
mv $1.a $1 # overwrite the original file

run it
swtchln.sh myfile brown

course there's lots of mods you can make to this, but you get the gist of it.

[Ross W]

close