Your terragrunt (or terraform) plan is 4,000 lines. Only two of them matter.

You know the ritual. terragrunt run --all -- plan Then you scroll. Past forty units of Refreshing state… . Past the ninth identical count instance. Past a tags_all.LastModified that changes on every single run because your CI stamps a timestamp into it. Somewhere in there are the two lines you actually needed to see — probably the # forces replacement on a database. You scroll back up. You lose it. You pipe it to a file and grep for must be replaced . You approve anyway, because it's 6pm. I got tired of that, so I wrote tgsieve . What it does It runs the plan for you, reads the structured output instead of the prose, throws away the noise you declared as noise, collapses everything that repeats, and prints what's left. DESTROY / REPLACE (1) envs/prod/a ± aws_db_instance.main engine_version "14.7" → "15.3" forces replacement UPDATE (5) 5 units envs/dev/a, envs/dev/b, envs/prod/a, +2 more ~ null_resource.pin triggers.region "eu-central-1" → "us-west-2" SUMMARY ±1 replace ~5 update severity: 1 high, 5 medium hid 214 attributes across 3 rules (--explain to see them) That's five units of a real terragrunt plan — the same run terraform prints as several hundred lines. The report nests three deep — where , then what , then which fields : UPDATE (5) envs/prod/c ← the unit, said once ~ aws_s3_bucket.this ← the resource tags_all.entity "tgb" → "tgc" ← the attributes that changed A change that's identical across units replaces the directory with the set it covers, so the first column always answers the same question: where . It doesn't scrape text This matters, because the obvious implementation is fragile garbage. You might reach for terragrunt run --all -- plan -json . It doesn't work: terragrunt forwards terraform's own NDJSON straight through, so lines from units running in parallel interleave with no way to tell them apart. So tgsieve asks terragrunt for machine-readable artifacts and reads those: What Flag it passes What it gets per-unit plans --json-out-dir one tfplan.j