recs-xform
Help from: --help-basic: Usage: recs-xform <args> <expr> [<files>] <expr> is evaluated as perl on each record of input (or records from <files>) with $r set to a App::RecordStream::Record object and $line set to the current line number (starting at 1). All records are printed back out (changed as they may be). If $r is set to an ARRAY ref in the expr, then the values of the array will be treated as records and outputed one to a line. The values of the array may either be a hash ref or a App::RecordStream::Record object. The original record will not be outputted in this case. There are two helper methods: push_input and push_output. Invoking push_input on a Record object or hash will cause the next record to be processed to be the indicated record. You may pass multiple records with one call. Similarly push_output causes the next record to be output to be the passed record(s). If push_record is called, the original record will not be output in this case. (call push_record($r) if you want that record also outputted). You may call these methods from a --pre-snippet or a --post-snippet. You may also call push_output() without any argument to suppress the outputting of the current record --e a perl snippet to execute, optional --E the name of a file to read as a perl snippet --M module[=...] execute "use module..." before executing snippet; same behaviour as perl -M --m module[=...] same as -M, but by default import nothing --A NUM Make NUM records after this one available in $A (closest record to current in first position) --B NUM Make NUM records before this one available in $B (closest record to current in first position) --C NUM Make NUM records after this one available in $A and $B, as per -A NUM and -B NUM --post-snippet SNIP A snippet to run once the stream has completed --pre-snippet SNIP A snippet to run before the stream starts --filename-key|fk <keyspec> Add a key with the source filename (if no filename is applicable will put NONE) Help Options: --help-all Output all help for this script --help This help screen --help-keyspecs Help on keyspecs, a way to index deeply and with regexes --help-snippet Help on code snippets Examples: Add line number to records recs-xform '$r->{line} = $line' Rename field old to new, remove field a recs-xform '$r->rename("old", "new"); $r->remove("a");' Remove fields which are not "a", "b", or "c" recs-xform '$r->prune_to("a", "b", "c")' Double records recs-xform '$r = [{%$r}, {%$r}]' Double records with function interface recs-xform 'push_output($r, $r);' Move a value from the previous record to the next record recs-xform -B 1 '{{before_val}} = $B->[0]' Help from: --help-keyspecs: KEY SPECS A key spec is short way of specifying a field with prefixes or regular expressions, it may also be nested into hashes and arrays. Use a '/' to nest into a hash and a '#NUM' to index into an array (i.e. #2) An example is in order, take a record like this: {"biz":["a","b","c"],"foo":{"bar 1":1},"zap":"blah1"} {"biz":["a","b","c"],"foo":{"bar 1":2},"zap":"blah2"} {"biz":["a","b","c"],"foo":{"bar 1":3},"zap":"blah3"} In this case a key spec of 'foo/bar 1' would have the values 1,2, and 3 in the respective records. Similarly, 'biz/#0' would have the value of 'a' for all 3 records You can also prefix key specs with '@' to engage the fuzzy matching logic Fuzzy matching works like this in order, first key to match wins 1. Exact match ( eq ) 2. Prefix match ( m/^/ ) 3. Match anywehre in the key (m//) So, in the above example '@b/#2', the 'b' portion would expand to 'biz' and 2 would be the index into the array, so all records would have the value of 'c' Simiarly, @f/b would have values 1, 2, and 3 You can escape / with a \. For example, if you have a record: {"foo/bar":2} You can address that key with foo\/bar Help from: --help-snippet: CODE SNIPPETS: Recs code snippets are perl code, with one exception. There a couple of variables predefined for you, and one piece of special syntax to assist in modifying hashes. Special Variables: $r - the current record object. This may be used exactly like a hash, or you can use some of the special record functions, see App::RecordStream::Record for more information $line - This is the number of records run through the code snippet, starting at 1. For most scripts this corresponds to the line number of the input to the script. $filename - The filename of the originating record. Note: This is only useful if you're passing filenames directly to the recs script, piping from other recs scripts or from cat, for instance, will not have a useful filename. Special Syntax Use {{search_string}} to look for a string in the keys of a record, use / to nest keys. You can nest into arrays by using an index. If you are vivifying arrays (if the array doesn't exist, prefix your key with # so that an array rather than a hash will be created to put a / in your key, escape it twice, i.e. \/ This is exactly the same as a key spec that is always prefaced with a @, see 'man recs' for more info on key specs For example: A record that looks like: { "foo" : { "bar 1" : 1 }, "zoo" : 2} Could be accessed like this: # value of zoo # value of $r->{foo}->{bar 1}: (comma separate nested keys) {{zoo}} {{foo/ar 1}} # Even assign to values (set the foo key to the value 1) {{foo}} = 1 # And auto, vivify {{new_key/array_key/#0}} = 3 # creates an array within a hash within a hash # Index into an array {{array_key/#3}} # The value of index 3 of the array ref under the 'array_key' hash key. This matching is a fuzzy keyspec matching, see --help-keyspecs for more details.
To install App::RecordStream, copy and paste the appropriate command in to your terminal.
cpanm
cpanm App::RecordStream
CPAN shell
perl -MCPAN -e shell install App::RecordStream
For more information on module installation, please visit the detailed CPAN module installation guide.