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Crawl Job Extractor
The crawl job extractor creates a file containing a list of domains along with known URLs.
This is consumed by processes/crawling-process.
Usage
The crawl job extractor has three modes of operation:
# 1 grab domains from the database
./crawl-job-extractor file.out
# 2 grab domains from a file
./crawl-job-extractor file.out -f domains.txt
# 3 grab domains from the command line
./crawl-job-extractor file.out domain1 domain2 ...
- When only a single argument is passed, the file name to write to, it will create a complete list of domains and URLs known to the system from the list of already indexed domains, as well as domains from the CRAWL_QUEUE table in the database.
- When the command line is passed like
./crawl-job-extractor output-file -f domains.txt, domains will be read from non-blank and non-comment lines in the file. - In other cases, the 2nd argument onward to the command will be interpreted as domain-names.
In the last two modes, if the crawl-job-extractor is able to connect to the database, it will use information from the link database to populate the list of URLs for each domain, otherwise it will create a spec with only the domain name and the index address, so the crawler will have to figure out the rest.
The crawl-specification is zstd-compressed json.
Tricks
Joining two specifications
Two or more specifications can be joined with a shell command on the form
$ zstdcat file1 file2 | zstd -o new-file
Inspection
The file can also be inspected with zstdless,
or combinations like zstdcat file | jq