eosio-blocklog is a command-line interface (CLI) utility that allows node operators to perform low-level tasks on the block logs created by a nodeos instance. eosio-blocklog can perform one of the following operations:

  • Convert a range of blocks to JSON format, as single objects or array.
  • Generate blocks.index from blocks.log in blocks directory.
  • Trim blocks.log and blocks.index between a range of blocks.
  • Perform consistency test between blocks.log and blocks.index.
  • Output the results of the operation to a file or stdout (default).


Option (=default) Description
--blocks-dir arg (="blocks") The location of the blocks directory (absolute path or relative to the current directory)
-o [ --output-file ] arg The file to write the generated output to (absolute or relative path). If not specified then output is to stdout
-f [ --first ] arg (=0) The first block number to log or the first block to keep if trim-blocklog specified
-l [ --last ] arg (=4294967295) the last block number to log or the last block to keep if trim-blocklog specified
--no-pretty-print Do not pretty print the output. Useful if piping to jq to improve performance
--as-json-array Print out JSON blocks wrapped in JSON array (otherwise the output is free-standing JSON objects)
--make-index Create blocks.index from blocks.log. Must give blocks-dir location. Give output-file relative to current directory or absolute path (default is <blocks-dir>/blocks.index)
--trim-blocklog Trim blocks.log and blocks.index. Must give blocks-dir and first and/or last options.
--smoke-test Quick test that blocks.log and blocks.index are well formed and agree with each other
-h [ --help ] Print this help message and exit


When eosio-blocklog is launched, the utility attempts to perform the specified operation, then yields the following possible outcomes:

  • If successful, the selected operation is performed and the utility terminates with a zero error code (no error).
  • If unsuccessful, the utility outputs an error to stderr and terminates with a non-zero error code (indicating an error).