Interrogate one request with curl

Problem

What becomes confusing, fragile, or impossible without understanding interrogate one request with curl? This lesson answers that through explanation, a worked example, two runnable exercises, and a reference solution. No teacher-supplied worksheet is required.

Before integrated development environments, the operating system, terminal, files, and text streams were the environment. Their small composable interfaces still underpin modern tooling.

Concept explanation

Interrogate one request with curl belongs to “The network beneath the URL”. interrogate one request with curl ships as one thin, inspectable slice of an annotated request trace from DNS to response bytes.

For interrogate one request with curl, trace concrete input, state transition, output, and failure through an operating-system boundary made visible through bytes, files, processes, and exit status.

Programs are processes. They read bytes, transform state, write bytes, open files and sockets, then report success or failure through observable boundaries. Apply that model to supplied normal, boundary, and failure cases; each case below names its input and expected evidence.

Example bank

Compare normal, boundary, failure, and cross-layer cases. Predict each observation before revealing the explanation.

Worked example

Start from supplied lab.sh. Focus: Add interrogate one request with curl to an annotated request trace from DNS to response bytes; demo it with: Resolve example.com, connect with curl -v, and save response headers and body separately.

1. Run: chmod +x lab.sh && ./lab.sh
2. Save baseline evidence. Use wc, od, stat, ps, lsof, curl, or Git plumbing as appropriate; save raw output before interpretation.
3. Boundary case: Document and test shipped slice under: Repeat with redirects disabled, then enabled.
4. Failure case: Add recovery behavior and a regression check for: Request an unused local port with a two-second timeout.

RESULT
Fresh clone or blank directory can run documented slice and reproduce: Trace identifies resolved address, TLS/HTTP exchange, status, headers, body size, and connection failure. Starter-level baseline: Command exits 0, prints a byte count, then prints hexadecimal and character views of the same file.

Starter material

Create lab.sh, paste this exact content, then run the command below.

#!/usr/bin/env sh
set -eu
lab="${TMPDIR:-/tmp}/reforging-lab"
mkdir -p "$lab"
printf '%s\n' 'baseline: interrogate one request with curl' > "$lab/input.txt"
printf 'bytes: ' && wc -c < "$lab/input.txt"
od -An -tx1 -c "$lab/input.txt"

STOP / CLEANUPNo background process. Keep generated evidence files for your notebook.

Independent exercise

Make it recoverable: interrogate one request with curl

1. Create second case from blank file: Document and test shipped slice under: Repeat with redirects disabled, then enabled.
2. Then create controlled failure: Add recovery behavior and a regression check for: Request an unused local port with a two-second timeout.
3. Use Ghostty · tmux · hx · shell · curl · Git to prove behavior, then repair controlled failure.
4. Compare result against supplied acceptance checks and reference approach before marking complete.

Expected result

• Fresh clone or blank directory can run documented slice and reproduce: Trace identifies resolved address, TLS/HTTP exchange, status, headers, body size, and connection failure.
• Command exits 0, prints a byte count, then prints hexadecimal and character views of the same file.
• Controlled interrogate one request with curl failure produces captured evidence; repair restores stated invariant without hiding error.

Hints

Solution

Attempt both exercises before opening reference approach.