CODEWITHSUNDEEP
linuxshellunixfiltersplit
josiah
josiah

Reputation: 1414

(L)unix - split then filter, sending the result to stdout

I can't seem to find a good way to do this using Unix/Linux commands (without writing a script). I'm thinking this can be done, though.

What I want to do is read the contents of a file, split them by some delimiter, and then discard any segments that don't match a RegEx (essentially, a map-filter-reduce problem).

something like 

cat original-file.sql | split --separator=';' | pcregrep -M '(.|\n)*needed_schema(.|\n)*' | result-file.sql

so that the result file only contains SQL statements that include 'needed_schema' in the statement.

original-file.sql

SELECT * 
FROM information_schema.tables 
WHERE table_schema = 'public'
;

SELECT *
FROM needed_schema.some_table
WHERE some_col = 'some value'
;

SELECT *
FROM needed_schema.some_other_table
WHERE some_other_col = 'some other value'
;

result-file.sql 

SELECT *
FROM needed_schema.some_table
WHERE some_col = 'some value'
;     

SELECT *
FROM needed_schema.some_other_table
WHERE some_other_col = 'some other value'
;

Upvotes: 1

Views: 175

Answers (1)

Andreas Louv
Andreas Louv

Reputation: 47099

Consider using awk and assign RS (Record Separator) and ORS (Output Record Separator):

$ awk '/needed_schema/' RS=';' ORS=';' input


SELECT *
FROM needed_schema.some_table
WHERE some_col = 'some value'
;

SELECT *
FROM needed_schema.some_other_table
WHERE some_other_col = 'some other value'
;

The regex is not PCRE but Extended Regular Expression

Upvotes: 2

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