Select lines based on lines above them
Clash Royale CLAN TAG#URR8PPP
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I have a list of items, from which I want to select the names of active items:
item
status: "Active"
properties
key_a: value
id: 42
name: "Foo"
item
status: "Disabled"
properties
key_b: value
id: 12
name: "Bar"
item
status: "Active"
id: 2
name: "Baz"
I know that I can extract the names using capture groups with pcregrep:
$ cat list.txt | pcregrep -o1 -i '^ name: "(.*)"'
Foo
Bar
Baz
Using an OR expression, I can also get a list of repeated status values and names:
$ cat list.txt | pcregrep -o2 -i '^ (status|name): "(.*)"'
Active
Foo
Disabled
Bar
Active
Baz
Finally, I need to filter the names in the list based on their preceding lines. How can I do this?
The final output should be:
Foo
Baz
text-processing grep pcregrep
asked Aug 10 at 16:36
danijar
352312
 |Â
show 2 more comments
up vote
0
down vote
favorite
I have a list of items, from which I want to select the names of active items:
item
status: "Active"
properties
key_a: value
id: 42
name: "Foo"
item
status: "Disabled"
properties
key_b: value
id: 12
name: "Bar"
item
status: "Active"
id: 2
name: "Baz"
I know that I can extract the names using capture groups with pcregrep:
$ cat list.txt | pcregrep -o1 -i '^ name: "(.*)"'
Foo
Bar
Baz
Using an OR expression, I can also get a list of repeated status values and names:
$ cat list.txt | pcregrep -o2 -i '^ (status|name): "(.*)"'
Active
Foo
Disabled
Bar
Active
Baz
Finally, I need to filter the names in the list based on their preceding lines. How can I do this?
The final output should be:
Foo
Baz
text-processing grep pcregrep
asked Aug 10 at 16:36
danijar
352312
Why don't thepropertieshave a closing brace?
– glenn jackman
Aug 10 at 23:28
I had the same question as asked by glenn jackman, what about the closing parens for the "properties" property. Secondly, you can have your result by feedingpcregrep's o/p to:sed -n 'N;s/^Activen//p'
– Rakesh Sharma
Aug 11 at 3:09
@glennjackman Thanks for pointing that out -- I updated the example to add the missing braces.
– danijar
Aug 11 at 12:35
@RakeshSharma Thanks a lot, this works. Since this seems to be the easiest solution, would you mind creating an answer with a little explanation so I can accept it?
– danijar
Aug 11 at 12:36
Is this a JSON document? Why not use a JSON parser likejq?
– Kusalananda
Aug 11 at 12:38
 |Â
show 2 more comments
up vote
0
down vote
favorite
up vote
0
down vote
favorite
I have a list of items, from which I want to select the names of active items:
item
status: "Active"
properties
key_a: value
id: 42
name: "Foo"
item
status: "Disabled"
properties
key_b: value
id: 12
name: "Bar"
item
status: "Active"
id: 2
name: "Baz"
I know that I can extract the names using capture groups with pcregrep:
$ cat list.txt | pcregrep -o1 -i '^ name: "(.*)"'
Foo
Bar
Baz
Using an OR expression, I can also get a list of repeated status values and names:
$ cat list.txt | pcregrep -o2 -i '^ (status|name): "(.*)"'
Active
Foo
Disabled
Bar
Active
Baz
Finally, I need to filter the names in the list based on their preceding lines. How can I do this?
The final output should be:
Foo
Baz
text-processing grep pcregrep
asked Aug 10 at 16:36
danijar
352312
I have a list of items, from which I want to select the names of active items:
item
status: "Active"
properties
key_a: value
id: 42
name: "Foo"
item
status: "Disabled"
properties
key_b: value
id: 12
name: "Bar"
item
status: "Active"
id: 2
name: "Baz"
I know that I can extract the names using capture groups with pcregrep:
$ cat list.txt | pcregrep -o1 -i '^ name: "(.*)"'
Foo
Bar
Baz
Using an OR expression, I can also get a list of repeated status values and names:
$ cat list.txt | pcregrep -o2 -i '^ (status|name): "(.*)"'
Active
Foo
Disabled
Bar
Active
Baz
Finally, I need to filter the names in the list based on their preceding lines. How can I do this?
The final output should be:
Foo
Baz
text-processing grep pcregrep
text-processing grep pcregrep
asked Aug 10 at 16:36
danijar
352312
asked Aug 10 at 16:36
danijar
352312
edited Aug 11 at 12:34
asked Aug 10 at 16:36
danijar
352312
asked Aug 10 at 16:36
danijar
352312
asked Aug 10 at 16:36
danijar
352312
352312
Why don't thepropertieshave a closing brace?
– glenn jackman
Aug 10 at 23:28
I had the same question as asked by glenn jackman, what about the closing parens for the "properties" property. Secondly, you can have your result by feedingpcregrep's o/p to:sed -n 'N;s/^Activen//p'
– Rakesh Sharma
Aug 11 at 3:09
@glennjackman Thanks for pointing that out -- I updated the example to add the missing braces.
– danijar
Aug 11 at 12:35
@RakeshSharma Thanks a lot, this works. Since this seems to be the easiest solution, would you mind creating an answer with a little explanation so I can accept it?
– danijar
Aug 11 at 12:36
Is this a JSON document? Why not use a JSON parser likejq?
– Kusalananda
Aug 11 at 12:38
 |Â
show 2 more comments
Why don't thepropertieshave a closing brace?
– glenn jackman
Aug 10 at 23:28
I had the same question as asked by glenn jackman, what about the closing parens for the "properties" property. Secondly, you can have your result by feedingpcregrep's o/p to:sed -n 'N;s/^Activen//p'
– Rakesh Sharma
Aug 11 at 3:09
@glennjackman Thanks for pointing that out -- I updated the example to add the missing braces.
– danijar
Aug 11 at 12:35
@RakeshSharma Thanks a lot, this works. Since this seems to be the easiest solution, would you mind creating an answer with a little explanation so I can accept it?
– danijar
Aug 11 at 12:36
Is this a JSON document? Why not use a JSON parser likejq?
– Kusalananda
Aug 11 at 12:38
Why don't the
properties have a closing brace?– glenn jackman
Aug 10 at 23:28
Why don't the
properties have a closing brace?– glenn jackman
Aug 10 at 23:28
I had the same question as asked by glenn jackman, what about the closing parens for the "properties" property. Secondly, you can have your result by feeding
pcregrep's o/p to: sed -n 'N;s/^Activen//p' – Rakesh Sharma
Aug 11 at 3:09
I had the same question as asked by glenn jackman, what about the closing parens for the "properties" property. Secondly, you can have your result by feeding
pcregrep's o/p to: sed -n 'N;s/^Activen//p' – Rakesh Sharma
Aug 11 at 3:09
@glennjackman Thanks for pointing that out -- I updated the example to add the missing braces.
– danijar
Aug 11 at 12:35
@glennjackman Thanks for pointing that out -- I updated the example to add the missing braces.
– danijar
Aug 11 at 12:35
@RakeshSharma Thanks a lot, this works. Since this seems to be the easiest solution, would you mind creating an answer with a little explanation so I can accept it?
– danijar
Aug 11 at 12:36
@RakeshSharma Thanks a lot, this works. Since this seems to be the easiest solution, would you mind creating an answer with a little explanation so I can accept it?
– danijar
Aug 11 at 12:36
Is this a JSON document? Why not use a JSON parser like
jq?– Kusalananda
Aug 11 at 12:38
Is this a JSON document? Why not use a JSON parser like
jq?– Kusalananda
Aug 11 at 12:38
 |Â
show 2 more comments
4 Answers
4
active
oldest
votes
up vote
1
down vote
accepted
Since most of the heavy lifting has already been done by pcregrep, you can now pass on it' s o/p to this short sed snippet :
sed -ne 'N;s/^Activen//p'
which makes sed to look at 2 lines at a time, rather than the default of 1. The N command sticks the next line to the pattern space by separating with a newline n. Now, only if sed was able to remove the Active first line in the pattern space, is the remaining pattern space going to be printed. This is a conditional print. Otw nothing and -n shall ensure no autoprinting of the pattern space. HTH.
answered Aug 11 at 17:11
Rakesh Sharma
157113
add a comment |Â
up vote
2
down vote
I don't think you can do this with a grep variation alone (admittedly I don't know pcregrep). Try awk:
awk '/^ *status.*Active.$/ ACT = 1 /^ *name:/ && ACT gsub (/"/, "", $2); print $2; ACT = 0' file
Foo
Baz
answered Aug 10 at 17:04
RudiC
1,1837
pcregrepis is just grep built with Perl-compatible regular expressions.
– glenn jackman
Aug 11 at 13:55
add a comment |Â
up vote
1
down vote
You can use sed too
sed '/status.*Active/,/name/!d;/name/!d;s/[^"]*"([^"]*)"/1/' infile
answered Aug 10 at 18:32
ctac_
1,016116
add a comment |Â
up vote
1
down vote
You could also use the range operator of Perl and constrain it with a boolean condition to deal with nested parentheses in a block.
Normally, one would write a range in Perl as /re1/ ... /re2/, this will causeperl to select the blocks that begin with regex /re1/ and end on those lines that satisfy the regex /re2/. We could further constrain this, to, say: /re1/ ... /re2/ && $depth==0.
This will cause perl to select only those blocks that have an additional constraint of the depth being zero. Like in this case, the block ending happens only when the } is found that causes the depth count to fall to zero, OTW, the block accumulation continues past this mark as well.
perl -lne '
if ( // ... // && !$depth ) Â
up vote
2
down vote
I don't think you can do this with a grep variation alone (admittedly I don't know pcregrep). Try awk:
awk '/^ *status.*Active.$/ ACT = 1 /^ *name:/ && ACT gsub (/"/, "", $2); print $2; ACT = 0' file
Foo
Baz
answered Aug 12 at 11:20
Rakesh Sharma
58513
add a comment is found that causes the depth count to fall to zero, OTW, the block accumulation continues past this mark as well.
perl -lne '
if ( // ... // && !$depth )
if ( // ) $depth = /^h*itemh+h*$/ ? 0 : ++$depth;
elsif ( // ) print($name),undef($flag) if !$depth-- && $flag;
elsif ( /^h*status:h*"Active"h*$/ ) $flag = 1;
elsif ( /^h*name:h/ ) $name = (split /"/)[1];
' input.file
answered Aug 12 at 11:20
Rakesh Sharma
58513
answered Aug 12 at 11:20
Rakesh Sharma
58513
answered Aug 12 at 11:20
Rakesh Sharma
58513
answered Aug 12 at 11:20
Rakesh Sharma
58513
58513
add a comment |Â
add a comment |Â
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Why don't the
propertieshave a closing brace?– glenn jackman
Aug 10 at 23:28
I had the same question as asked by glenn jackman, what about the closing parens for the "properties" property. Secondly, you can have your result by feeding
pcregrep's o/p to:sed -n 'N;s/^Activen//p'– Rakesh Sharma
Aug 11 at 3:09
@glennjackman Thanks for pointing that out -- I updated the example to add the missing braces.
– danijar
Aug 11 at 12:35
@RakeshSharma Thanks a lot, this works. Since this seems to be the easiest solution, would you mind creating an answer with a little explanation so I can accept it?
– danijar
Aug 11 at 12:36
Is this a JSON document? Why not use a JSON parser like
jq?– Kusalananda
Aug 11 at 12:38