Bash Utility scripts

This section describes the bash utilities that are compatible with DFTracer logs

Handling .pfw files

The DFTracer format with extension .pfw is uncompressed file which can be viewed using the following utilities.

  1. vim : Edit .pfw files

  2. cat, head, or tail: view portion of the pfw files

Handling .pfw.gz files

The DFtracer compressed format with .pfw extension can be first decompressed using gzip and then piped to the above .pfw utilities.

gzip -c -d `echo *.gz` | head

Extracting JSON data

Once the uncompressed data is parsed. The JSON utility jq can be used to parse args.

In each case we have to remove the first [ which has been added to support perfetto ui.

For uncompressed files .. code-block:: bash

cat *.pfw | grep -i “[^#[]” | jq -c ‘.’

For compressed files .. code-block:: bash

gzip -c -d echo *.gz | grep -i “[^#[]” | jq -c ‘.’

We can extract specific fields from these JSON lines as follows

  1. jq -c ‘.name’: extracts all the names of events

  2. jq -c ‘.cat’: extracts all the category of events

  3. jq -c ‘.args.hostname’: extracts the fields from extra args like hostname in this case.

Useful querying using jq

Extract unique functions with their counts from traces.

cat *.pfw | grep -i "[^#[]" | jq -c '.name' | sort | uniq -c

Extract unique categories with their counts from traces.

cat *.pfw | grep -i "[^#[]" | jq -c '.cat' | sort | uniq -c

Extract unique process id and thread id combination with their counts from traces.

cat *.pfw | grep -i "[^#[]" | jq -c '"\(.pid) \(.tid)"' | sort | uniq -c

Extract min timestamp

cat *.pfw | grep -i "[^#[]" | jq -c '.ts | tonumber' | sort -n | tail -1

Extract max timestamp

cat *.pfw | grep -i "[^#[]" | jq -c '.ts | tonumber' | sort -n | tail -n 1

For more commands on jq refer to JQ Manual.