curl - HTTP-Client und Datenübertragung

Umfassende curl-Befehle für HTTP-Anfragen, API-Tests und Datenübertragung auf allen Plattformen.

Grundlegende HTTP-Anfragen

GET-Anfragen

Befehl	Beschreibung
`curl https://api.example.com`	Grundlegender GET-Request
`curl -v https://api.example.com`	Ausführliche Ausgabe mit Headern
`curl -i https://api.example.com`	Antwort-Header einschließen
`curl -I https://api.example.com`	HEAD-Anfrage nur
`curl -L https://example.com`	Redirects folgen

POST-Anfragen

Befehl	Beschreibung
`curl -X POST https://api.example.com`	Grundlegender POST-Request
`curl -d "data" https://api.example.com`	POST mit Daten
`curl -d @file.json https://api.example.com`	POST-Daten aus Datei
`curl -F "file=@upload.txt" https://api.example.com`	Datei-Upload

Andere HTTP-Methoden

Befehl	Beschreibung
`curl -X PUT -d "data" https://api.example.com`	PUT-Anfrage
`curl -X DELETE https://api.example.com/item/1`	DELETE-Anfrage
`curl -X PATCH -d "data" https://api.example.com`	PATCH-Anfrage

Header und Authentifizierung

Benutzerdefinierte Header

Befehl	Beschreibung
`curl -H "Content-Type: application/json" url`	Content-Typ festlegen
`curl -H "Authorization: Bearer token" url`	Bearer-Token-Authentifizierung
`curl -H "User-Agent: MyApp/1.0" url`	Benutzerdefinierter User Agent
`curl -H "Accept: application/xml" url`	Accept-Header

Authentifizierungsmethoden

Befehl	Beschreibung
`curl -u username:password url`	Basis-Authentifizierung
`curl -u username url`	Passwort eingeben
`curl --oauth2-bearer token url`	OAuth2 Bearer-Token
`curl --digest -u user:pass url`	Digest-Authentifizierung

API-Schlüssel-Authentifizierung

# API key in header
curl -H "X-API-Key: your-api-key" https://api.example.com

# API key in query parameter
curl "https://api.example.com?api_key=your-api-key"

# Multiple headers
curl -H "Authorization: Bearer token" \
     -H "Content-Type: application/json" \
     https://api.example.com

Datenformate

JSON-Daten

# POST JSON data
curl -X POST \
     -H "Content-Type: application/json" \
     -d '\\\\{"name":"John","age":30\\\\}' \
     https://api.example.com/users

# JSON from file
curl -X POST \
     -H "Content-Type: application/json" \
     -d @data.json \
     https://api.example.com/users

Formulardaten

# URL-encoded form data
curl -d "name=John&age=30" https://api.example.com/users

# Multipart form data
curl -F "name=John" -F "age=30" https://api.example.com/users

# File upload with form data
curl -F "file=@document.pdf" \
     -F "description=Important document" \
     https://api.example.com/upload

XML-Daten

# POST XML data
curl -X POST \
     -H "Content-Type: application/xml" \
     -d '<user><name>John</name><age>30</age></user>' \
     https://api.example.com/users

Dateioperationen

Dateien herunterladen

Befehl	Beschreibung
`curl -O https://example.com/file.zip`	Download mit originalem Namen
`curl -o myfile.zip https://example.com/file.zip`	Download mit benutzerdefiniertem Namen
`curl -C - -O https://example.com/file.zip`	Download unterbrechen fortsetzen
`curl --limit-rate 100k -O url`	Download-Geschwindigkeit begrenzen

Dateien hochladen

Befehl	Beschreibung
`curl -T file.txt ftp://server/path/`	Upload über FTP
`curl -F "file=@upload.txt" url`	HTTP-Datei-Upload
`curl --upload-file file.txt url`	PUT Datei-Upload

Mehrere Dateien

# Download multiple files
curl -O https://example.com/file1.zip -O https://example.com/file2.zip

# Upload multiple files
curl -F "file1=@doc1.pdf" -F "file2=@doc2.pdf" https://api.example.com/upload

Erweiterte Optionen

Timeouts und Wiederholungen

Befehl	Beschreibung
`curl --connect-timeout 10 url`	Verbindungs-Timeout (Sekunden)
`curl --max-time 30 url`	Maximale Gesamtzeit
`curl --retry 3 url`	Bei Fehler erneut versuchen
`curl --retry-delay 5 url`	Verzögerung zwischen Wiederholungsversuchen

SSL/TLS-Optionen

Befehl	Beschreibung
`curl -k url`	SSL-Zertifikatsfehler ignorieren
`curl --cacert ca.pem url`	Benutzerdefiniertes CA-Zertifikat verwenden
`curl --cert client.pem url`	Client-Zertifikat verwenden
`curl --tlsv1.2 url`	TLS-Version erzwingen

Proxy und Netzwerk

Befehl	Beschreibung
`curl --proxy proxy.example.com:8080 url`	HTTP-Proxy verwenden
`curl --socks5 proxy.example.com:1080 url`	SOCKS5-Proxy verwenden
`curl --interface eth0 url`	Verwenden Sie eine bestimmte Netzwerkschnittstelle
`curl --dns-servers 8.8.8.8 url`	Verwenden Sie benutzerdefinierte DNS-Server

Ausgabe und Formatierung

Ausgabekontrolle

Befehl	Beschreibung
`curl -s url`	Silent-Modus (kein Fortschritt)
`curl -S url`	Zeige Fehler auch im stillen Modus
`curl -o /dev/null url`	Ausgabe verwerfen
`curl -w "%\\{http_code\\}" url`	Zeige nur HTTP-Statuscode

Antwortinformationen

# Get detailed timing information
curl -w "@curl-format.txt" https://example.com

# curl-format.txt content:
#     time_namelookup:  %\\\\{time_namelookup\\\\}\n
#        time_connect:  %\\\\{time_connect\\\\}\n
#     time_appconnect:  %\\\\{time_appconnect\\\\}\n
#    time_pretransfer:  %\\\\{time_pretransfer\\\\}\n
#       time_redirect:  %\\\\{time_redirect\\\\}\n
#  time_starttransfer:  %\\\\{time_starttransfer\\\\}\n
#                     ----------\n
#          time_total:  %\\\\{time_total\\\\}\n

JSON-Verarbeitung

# Pretty print JSON with jq
curl -s https://api.example.com/users|jq '.'

# Extract specific fields
curl -s https://api.example.com/users|jq '.[]|.name'

# Filter results
curl -s https://api.example.com/users|jq '.[]|select(.age > 25)'

Testen und Debuggen

API-Tests

Would you like me to continue with the remaining sections or provide translations for the numbered placeholders?```bash

Test REST API endpoints

curl -X GET https://api.example.com/users curl -X POST -d ’\\{“name”:“John”\\}’ https://api.example.com/users curl -X PUT -d ’\\{“name”:“Jane”\\}’ https://api.example.com/users/1 curl -X DELETE https://api.example.com/users/1

Test with different content types

curl -H “Accept: application/json” https://api.example.com/users curl -H “Accept: application/xml” https://api.example.com/users


### Performance Testing
```bash
# Measure response time
curl -w "Total time: %\\\\{time_total\\\\}s\n" -o /dev/null -s https://example.com

# Test multiple requests
for i in \\\\{1..10\\\\}; do
  curl -w "%\\\\{time_total\\\\}\n" -o /dev/null -s https://example.com
done

Error Handling

# Check HTTP status codes
http_code=$(curl -s -o /dev/null -w "%\\\\{http_code\\\\}" https://example.com)
if [ $http_code -eq 200 ]; then
    echo "Success"
else
    echo "Error: HTTP $http_code"
fi

Configuration and Scripts

Configuration File

# ~/.curlrc configuration file
user-agent = "MyApp/1.0"
connect-timeout = 10
max-time = 30
show-error
silent

Bash Scripting

#!/bin/bash
# API testing script

BASE_URL="https://api.example.com"
API_KEY="your-api-key"

# Function to make authenticated requests
api_request() \\\\{
    local method=$1
    local endpoint=$2
    local data=$3

    curl -X "$method" \
         -H "Authorization: Bearer $API_KEY" \
         -H "Content-Type: application/json" \
         $\\\\{data:+-d "$data"\\\\} \
         "$BASE_URL$endpoint"
\\\\}

# Usage examples
api_request GET "/users"
api_request POST "/users" '\\\\{"name":"John","email":"john@example.com"\\\\}'

Security Best Practices

Secure Authentication

# Use environment variables for sensitive data
export API_TOKEN="your-secret-token"
curl -H "Authorization: Bearer $API_TOKEN" https://api.example.com

# Read credentials from file
curl -K credentials.txt https://api.example.com

# credentials.txt:
# header = "Authorization: Bearer your-token"

Certificate Verification

# Always verify SSL certificates in production
curl --cacert /path/to/ca-bundle.crt https://api.example.com

# For development only (not recommended for production)
curl -k https://self-signed.example.com

Common Use Cases

Web Scraping

# Download webpage
curl -L https://example.com > page.html

# Follow redirects and save cookies
curl -L -c cookies.txt -b cookies.txt https://example.com

# Set user agent to avoid blocking
curl -H "User-Agent: Mozilla/5.0 (compatible; bot)" https://example.com

API Integration

# GitHub API example
curl -H "Authorization: token your-github-token" \
     https://api.github.com/user/repos

# Weather API example
curl "https://api.openweathermap.org/data/2.5/weather?q=London&appid=your-api-key"

# Slack webhook example
curl -X POST \
     -H "Content-Type: application/json" \
     -d '\\\\{"text":"Hello from curl!"\\\\}' \
     https://hooks.slack.com/services/YOUR/SLACK/WEBHOOK

File Transfer

# Upload to cloud storage
curl -X PUT \
     -H "Authorization: Bearer token" \
     --upload-file document.pdf \
     https://api.storage.com/files/document.pdf

# Download with progress bar
curl --progress-bar -O https://example.com/largefile.zip

Troubleshooting

Common Issues

Problem	Lösung
SSL certificate errors	Use `-k` for testing, fix certificates for production
Connection timeout	Increase `--connect-timeout` value
Slow downloads	Use `--limit-rate` to control bandwidth
Authentication failures	Überprüfe Anmeldeinformationen und Authentifizierungsmethode

Debugging Commands

# Verbose output for debugging
curl -v https://example.com

# Trace all network activity
curl --trace trace.txt https://example.com

# Show only headers
curl -I https://example.com

# Test connectivity
curl -I --connect-timeout 5 https://example.com