CODEWITHSUNDEEP
linuxunixawksed
keshav
keshav

Reputation: 33

Have to Replace a text which is in first row second column using linux

I have a file which having content like below.i want to replace text which is in first row second column from text which is stored in variable called var please help me out.

awk 'FNR==NR{a[NR]=$2;next}
     {$1=a[FNR]}1' CT-ColorMaster_3.0.0--ir48-48_build-48.mf var

Content of file.mf

SHA1(CT-ColorMaster_3.0.0--ir48-48_build-48.ovf)= **65769231a386fad1d7ed210422216a52ae6e00e1**
SHA1(CT-ColorMaster_3.0.0--ir48-48_build-48-disk1.vmdk)= b0de466259d30bd973f603adba746814b97e8946

Thanks.

Upvotes: 1

Views: 824

Answers (3)

user unknown
user unknown

Reputation: 36229

sed

var=foobar; sed -r "1s/^([^ ]+) [^ ]+/\1 $var/" file.mf
SHA1(CT-ColorMaster_3.0.0--ir48-48_build-48.ovf)= foobar
SHA1(CT-ColorMaster_3.0.0--ir48-48_build-48-disk1.vmdk)= b0de466259d30bd973f603adba746814b97e8946

The sed -r uses extended regular expressions, which is needed, to make the + work.

1s means to operate only on line 1, s = substitute.

'[^ ]+ ' is a common pattern, to search not greedy for a blank. As many non-blank-characters as you like, followed by a blank. Replace the following with $var.

With -i, you can change a file in place:

var=foobar
sed -i.bak -r "1s/^([^ ]+) [^ ]+/\1 $var/" file.mf

generates a backup file.mf.bak from file.mf, and writes the changes to file.mf .

Without backup:

var=foobar
sed -i -r "1s/^([^ ]+) [^ ]+/\1 $var/" file.mf

If your sed lacks the -i-option, use

sed -r "1s/^([^ ]+) [^ ]+/\1 $var/" file.mf > file.mf.new 
mv file.mf file.mf.bak
mv file.mf.new file.mf

Upvotes: 3

Walter A
Walter A

Reputation: 19982

The problem in your attempt is that the var is not a file. You can use a trick avoiding temporary files with <(echo "${var}"):

awk 'FNR==NR{a[NR]=$2;next}
     {$1=a[FNR]}1' CT-ColorMaster_3.0.0--ir48-48_build-48.mf <(echo "${var}")

When the variable var is one line, your solution can be simplified into the solution of @kvantour.

Upvotes: 1

kvantour
kvantour

Reputation: 26471

Is this what you try to achieve?

var="this is some text"
awk -v var=$var `(NR==1){$2=var}1` file.mf

This outputs:

SHA1(CT-ColorMaster_3.0.0--ir48-48_build-48.ovf)= this is some text 
SHA1(CT-ColorMaster_3.0.0--ir48-48_build-48-disk1.vmdk)= b0de466259d30bd973f603adba746814b97e894

Upvotes: 1

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