CODEWITHSUNDEEP
awk
Abbas
Abbas

Reputation: 3284

How to extract string from a file in bash

I have a file called DB_create.sql which has this line

CREATE DATABASE testrepo;

I want to extract only testrepo from this. So I've tried

cat DB_create.sql | awk '{print $3}'

This gives me testrepo;

I need only testrepo. How do I get this ?

Upvotes: 1

Views: 1134

Answers (4)

Carlos Pascual
Carlos Pascual

Reputation: 1126

Use your own code but adding the function sub():

cat DB_create.sql | awk '{sub(/;$/, "",$3);print $3}'

Although it's better not using cat. Here you can see why: Comparison of cat pipe awk operation to awk command on a file

So better this way:

awk '{sub(/;$/, "",$3);print $3}' file

Upvotes: 1

anubhava
anubhava

Reputation: 785146

Using gnu awk, you can set record separator as ; + line break:

awk -v RS=';\r?\n' '{print $3}' file.sql

testrepo

Or using any POSIX awk, just do a call to sub to strip trailing ;:

awk '{sub(/;$/, "", $3); print $3}' file.sql

testrepo

Upvotes: 3

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626826

You can use

awk -F'[;[:space:]]+' '{print $3}' DB_create.sql

where the field separator is set to a [;[:space:]]+ regex that matches one or more occurrences of ; or/and whitespace chars. Then, Field 3 will contain the string you need without the semi-colon.

More pattern details:

  • [ - start of a bracket expression
    • ; - a ; char
    • [:space:] - any whitespace char
  • ] - end of the bracket expression
  • + - a POSIX ERE one or more occurrences quantifier.

See the online demo.

Upvotes: 1

RavinderSingh13
RavinderSingh13

Reputation: 133518

With your shown samples, please try following.

awk -F'[ ;]' '{print $(NF-1)}' DB_create.sql

OR

awk -F'[ ;]' '{print $3}' DB_create.sql

OR without setting any field separators try:

awk '{sub(/;$/,"");print $3}'  DB_create.sql

Simple explanation would be: making field separator as space OR semi colon and then printing 2nd last field($NF-1) which is required by OP here. Also you need not to use cat command with awk because awk can read Input_file by itself.

Upvotes: 3

Related Questions