CODEWITHSUNDEEP
bashsedcut
Steve Park
Steve Park

Reputation: 51

How to substring version value using sed?

Input strings are as follows.

6.5.1.2.3
6.10.3.9.6
7.2.0.0.0
10.11.12.13.4

And I want to extract first two digit and replace period character to underscore using sed 

6_5
6_10
7_2
10_11

When I used this:

sed 's/\./_/g' | cut -c 1-3

6_10, 10_11 result was not correct.

Is there any work around here?

Upvotes: 0

Views: 101

Answers (4)

fedorqui
fedorqui

Reputation: 289495

awk is also useful for such things. If you set the output field separator OFS:

$ awk -F"." -v OFS="_" '{print $1, $2}' file
6_5
6_10
7_2
10_11

But if you really need sed use back references (here with extended regular expressions — note that the option is sometimes -E and sometimes only basic regular expressions are supported by sed):

$ sed -r 's/([0-9]+)\.([0-9]+).*/\1_\2/' file
6_5
6_10
7_2
10_11

If you want to perform in-place replacing, you can either say awk/sed '...' file > tmp_file && mv tmp_file file or, use sed -i (on those platforms where it is supported, but note that there are differences between GNU sed and BSD (macOS) sed), or gawk -i inplace (GNU Awk).

Note in both cases I am using a single command instead of piping to another one.

Upvotes: 4

Мона_Сах
Мона_Сах

Reputation: 322

My awk solution would be :

$ echo "6.5.1.2.3
> 6.10.3.9.6
> 7.2.0.0.0
> 10.11.12.13.4" | awk 'BEGIN{FS=".";OFS="_"}{print $1,$2}'
6_5
6_10
7_2
10_11

Upvotes: 0

Kusalananda
Kusalananda

Reputation: 15603

The input is so simple it can be done easily with just cut and tr. Use cut to pick out the first two fields (delimited by .), and then use tr to change the dot to an underscore:

$ cut -d '.' -f 1,2 input | tr '.' '_'
6_5
6_10
7_2
10_11

Upvotes: 1

Florin Ghita
Florin Ghita

Reputation: 17643

You are almost there:

echo 1.2.3.4 | sed 's/\./_/g' | cut -d "_" -f1,2

(Escaped the dot with \, and specified the delimiter for cut.)

Upvotes: 1

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