Track 03 of 12 · Work with real input

Finding & Transforming Data

Find files safely and reshape text or structured data with focused command-line tools. Learn where record boundaries, quoting, and format-aware parsing matter.

Builds on:Terminal FoundationsStreams, Pipes & Text

Ten concepts, in learning order

Each lesson assumes the ideas above it and prepares you for the ones below.

  1. 01Finding files with findfind traverses directory trees from explicit starting points and evaluates an expression of tests and actions for each encountered pathname.
  2. 02Building arguments with xargsxargs reads input records and constructs one or more command invocations whose argument lists contain those records, subject to parsing and size options.
  3. 03Null-delimited filenamesA null-delimited pathname stream terminates each pathname with a zero byte, the one byte that cannot occur inside a Unix pathname component.
  4. 04Command substitutionCommand substitution runs a nested command and replaces the substitution with its standard output after removing trailing newline characters.
  5. 05Shell parameter expansionParameter expansion replaces forms beginning with $ with a parameter's value or a transformation such as a default, required-value check, length, or pattern removal.
  6. 06Stream editing with sedsed applies an ordered editing program to a stream of input records, using addresses to select records and commands to transform or emit them.
  7. 07Field processing with awkawk processes input as records split into fields and runs pattern-action rules that can filter, calculate, aggregate, and format output.
  8. 08Character translation with trtr reads standard input and translates, deletes, or squeezes characters according to two character sets, then writes the result to standard output.
  9. 09Splitting output with teetee copies bytes from standard input to standard output and simultaneously writes copies to one or more files.
  10. 10JSON on the command line with jqjq parses JSON values and applies filters that select, construct, transform, or serialize structured results.

Continue the curriculum

Next: Shell Scripts & Job Control

Turn reliable commands into maintainable scripts and control long-running work from an interactive shell. Practice explicit arguments, failures, jobs, and cleanup.

Open track 4