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Last updated: 7 June 2020
[Get coronavirus/Covid-19 statistics for your country, real-time or historical](#ee19)
[Force curl not to show the progress bar](#ee0)
[Download a web page via GET request setting Chrome version 74 as the User-Agent.](#ee1)
[Download a web page via GET request setting Googlebot version 2.1 as the User-Agent](#ee2)
[Download a page via https ignoring ceritficate errors](#ee3)
[Download a page using SOCKS5 proxy listening on 127.0.0.1 port 10443](#ee4)
[Download a page using SOCKS5 proxy listening on 127.0.0.1 port 10443 and use remote host to resolve the hostname](#ee5)
[Download a page and report time spent in every step starting with resolving](#ee6)
[Resolve IP address to the owner's Autonomous System Number by sending POST query with form fields to the Team Cymru whois server](#ee27)
[Make sure Curl follows redirections (`Location:`) automatically, also using the correct `Referer` on each redirection](#ee7)
[Send GET request with digest authentication](#ee8)
[Download a remote file only if it's newer than the local copy](#ee9)
[Enable support for compressed encoding in response, as the real browser would do](#ee10)
[Verify CORS functionality of a website](#ee11)
[Convert Curl command into ready to be compiled C source file](#ee12)
[Display just the HTTP response code](#ee13)
[Get a page using specific version of HTTP protocol](#ee25)
[Download file with SCP protocol](#ee14)
[Get external IP address of the machine where the curl is installed](#ee15)
[Send e-mail via SMTP](#ee16)
[Make curl resolve a hostname to the custom IP address you specify without modifying hosts file or using DNS server hacks](#ee17)
[Show how many redirects were followed fetching the URL](#ee18)
[Use your browser to prepare the complete curl command via "copy as curl" feature](#ee20)
[Test if a website supports the given cipher suite, e.g. obsolete sslv3](#ee21)
[Fetch multiple pages with predictable pattern in their URLs](#ee22)
[How to prevent errors on URLs that contain brackets](#ee23)
[Github: list names of all public repositories for a given user](#ee24)
[Display weather report for a given city](#ee26)
= curl examples cookbook
:homepage:
:toc:
<a name="ee19"></a>
### Get coronavirus/Covid-19 statistics for your country, real-time or historical
== Get coronavirus/Covid-19 statistics for your country, real-time or historical
Add your country code after the slash, e.g. for Israel "il".
```Bash
----
$ curl -L -s covid19.trackercli.com/il
╔══════════════════════════════════════════════════════════════════════╗
║ COVID-19 Tracker CLI v3.1.0 - Israel Update ║
@@ -54,73 +28,70 @@ $ curl -L -s covid19.trackercli.com/il
╟──────────────────────────────────────────────────────────────────────╢
║ Code: https://github.com/warengonzaga/covid19-tracker-cli ║
╚══════════════════════════════════════════════════════════════════════╝
```
----
Historical data:
```Bash
----
$ curl -L -s covid19.trackercli.com/history/il
```
----
<a name="ee0"></a>
### Force curl not to show the progress bar
== Force curl not to show the progress bar
Use `-s` option to make it silent:
```Bash
----
curl -o index.html -s https://yurisk.info
```
----
<hr>
<a name="ee1"></a>
### Download a web page via GET request setting Chrome version 74 as the User-Agent.
== Download a web page via GET request setting Chrome version 74 as the User-Agent.
Use `-A` to set User-Agent.
```Bash
----
curl -o Index.html -A "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" http://example.com
```
----
Resources: <a href="https://developers.whatismybrowser.com/useragents/explore/" target="_blank" rel="noopener"> https://developers.whatismybrowser.com/useragents/explore/</a>
<a name="ee2"></a>
### Download a web page via GET request setting Googlebot version 2.1 as the User-Agent.
== Download a web page via GET request setting Googlebot version 2.1 as the User-Agent.
```Bash
----
curl -o Index.html -A "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)" http://example.com
```
----
<a name="ee3"></a>
### Download a page via https ignoring ceritficate errors
== Download a page via https ignoring ceritficate errors
Add `-k` to ignore any SSL certificate warnings/errors.
```Bash
----
curl -k -o Index.html https://example.com
```
----
<a name="ee4"></a>
### Download a page using SOCKS5 proxy listening on 127.0.0.1 port 10443
== Download a page using SOCKS5 proxy listening on 127.0.0.1 port 10443
```Bash
----
curl -x socks5://localhost:10443 https://yurisk.info
```
----
<a name="ee5"></a>
### Download a page using SOCKS5 proxy listening on 127.0.0.1 port 10443 and use remote host to resolve the hostname
== Download a page using SOCKS5 proxy listening on 127.0.0.1 port 10443 and use remote host to resolve the hostname
```Bash
----
curl -x socks5h://localhost:10443 https://yurisk.info
```
----
The idea here is to tunnel DNS requests to the remote end of the tunnel as well, for example for privacy concerns to prevent <a href="https://en.wikipedia.org/wiki/DNS_leak" target="_blank" rel="noopener">DNS leak</a>.
<a name="ee6"></a>
### Download a page and report time spent in every step starting with resolving:
== Download a page and report time spent in every step starting with resolving:
Source: <a href="https://stackoverflow.com/questions/18215389/how-do-i-measure-request-and-response-times-at-once-using-curl" target="_blank" rel="noopener"> Stackoverflow</a>
- Step 1: Put the parameters to write into a file called say _curl-params_ (just for the convenience instead of CLI):
```Bash
----
time_namelookup: %{time_namelookup}\n
time_connect: %{time_connect}\n
time_appconnect: %{time_appconnect}\n
@@ -129,15 +100,15 @@ Source: <a href="https://stackoverflow.com/questions/18215389/how-do-i-measure-r
time_starttransfer: %{time_starttransfer}\n
----------\n
time_total: %{time_total}\n
```
----
- Step 2: Run the curl supplying this file _curl-params_:
```Bash
----
curl -w "@curl-params" -o /dev/null -s https://example.com
```
----
```Bash
----
time_namelookup: 0.062
time_connect: 0.062
@@ -147,90 +118,86 @@ curl -w "@curl-params" -o /dev/null -s https://example.com
time_starttransfer: 0.240
----------
time_total: 0.241
```
----
<a name="ee27"></a>
### Resolve IP address to the owner's Autonomous System Number by sending POST query with form fields to the Team Cymru whois server
== Resolve IP address to the owner's Autonomous System Number
Do so by sending POST query with form fields to the Team Cymru whois server
When sending any POST data with form fields, the first task is to get all the fields. The esiest way to do it is to browse to the page, fill the form, open the HTML code and write down fields and their values. I did it for the page at <a href="https://asn.cymru.com/" target=_blank rel="noopener">https://asn.cymru.com/</a> and noted 5 fields to fill with values, the field to place IP address to query for is `bulk_paste`. In curl you specify field values with `-F 'name=value'` option:
```bash
----
curl -s -X POST -F 'action=do_whois' -F 'family=ipv4' -F 'method_whois=whois' -F 'bulk_paste=35.1.33.192' -F 'submit_paste=Submit' https://asn.cymru.com/cgi-bin/whois.cgi | grep "|"
```
----
Output:
```bash
----
<PRE>AS | IP | AS Name
36375 | 35.1.33.192 | UMICH-AS-5, US
```
----
Resources: <a href="https://ec.haxx.se/http/http-post" target=_blank rel="noopener">https://ec.haxx.se/http/http-post</a>
<a name="ee7"></a>
### Make sure Curl follows redirections (`Location:`) automatically, using the correct `Referer` on each redirection
== Make sure Curl follows redirections (`Location:`) automatically, using the correct `Referer` on each redirection
```Bash
----
curl -L -e ';auto' -o index.html https://example.com
```
----
NOTE: All the downloaded pages will be appended to the same output file, here _index.html_.
<a name="ee8"></a>
### Send GET request with digest authentication
== Send GET request with digest authentication
```Bash
----
curl --digest http://user:pass@example.com/login
```
----
<a name="ee9"></a>
### Download a remote file only if it's newer than the local copy
== Download a remote file only if it's newer than the local copy
```Bash
----
curl -z index.html -o index.html https://example.com/index.html
```
----
NOTE: file to compare/download, here _index.html_, is compared for timestamp only, no content hashing or anything else.
<a name="ee10"></a>
### Enable support for compressed encoding in response, as a real browser would do
== Enable support for compressed encoding in response, as a real browser would do
```Bash
----
curl -compressed -o w3.css https://yurisk.info/theme/css/w3.css
```
----
Note: this option causes curl to sent `Accept-Encoding: gzip` in the request.
<a name="ee11"></a>
### Verify CORS functionality of a website
== Verify CORS functionality of a website
```Bash
----
curl -H "Access-Control-Request-Method: GET" -H "Origin: http://localhost" --head https://yurisk.info/2020/03/05/fortiweb-cookbook-content-routing-based-on-url-in-request-configuration/pic1.png
```
----
Output:
```Bash
----
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET
```
----
<a name="ee12"></a>
### Convert Curl command into ready to be compiled C source file
== Convert Curl command into ready to be compiled C source file
```Bash
----
curl -o index.html https://yurisk.info --libcurl index.c
```
----
The output file index.c will contain the source code to implement the same command using Curl C library:
```C
[source,c]
----
/********* Sample code generated by the curl command line tool **********
* All curl_easy_setopt() options are documented at:
@@ -279,88 +246,87 @@ int main(int argc, char *argv[])
}
/**** End of sample code ****/
```
----
You can now compile it to executable, provided you have `libcurl` library and its headers installed: `gcc index.c -lcurl -o index`
<a name="ee13"></a>
### Display just the HTTP response code
== Display just the HTTP response code
```Bash
----
curl -w '%{http_code}' --silent -o /dev/null https://yurisk.info
```
----
Output:
```Bash
----
200
```
----
<a name="ee25"></a>
### Get a page using specific version of HTTP protocol
```bash
== Get a page using specific version of HTTP protocol
----
curl --http2 -s -O https://yurisk.info
```
----
<a name="ee14"></a>
### Download file with SCP protocol
== Download file with SCP protocol
```Bash
----
curl scp://99.23.5.18:/root/pdf.pdf -o pdf.pdf -u root
```
----
Note: curl checks `~/.ssh/known_hosts` file to verify authenticityy of the remote server. If the remote server is not already in the `known_hosts`, curl will refuse to connect. To prevent it - connect to the remote server via SSH, this will add it to the known hosts. Also, curl should be compiled with support for `libssh2` library.
<a name="ee15"></a>
### Get external IP address of the machine where the curl is installed
== Get external IP address of the machine where the curl is installed
```Bash
----
curl -s http://whatismyip.akamai.com/
87.123.255.103
```
----
<a name="ee16"></a>
### Send e-mail via SMTP
== Send e-mail via SMTP
First, put the message body and From/To/Subject fields in a file:
```Bash
----
# cat message.txt
From: Joe Dow <joedow@example.com>
To: Yuri <yuri@yurisk.info>
Subject: Testing curl SMTP sending
Hi, curl can now send e-mails as well!
```
----
Now, send the e-mail using the created file and setting e-mail envelope on the CLI:
```Bash
curl -v smtp://aspmx.l.google.com/smtp.example.com --mail-from Joedow@example.com --mail-rcpt yuri@yurisk.info --upload-file message.txt
```
Here:
`aspmx.l.google.com` - the mail server for the recipient domain (`curl` does NOT look for the MX record itself).
`smtp.example.com` (Optional) - domain the `curl` will use in greeting the mail server (HELO/EHLO).
`--mail-from` - sender address set in the envelope.
`--mail-rcpt` - recipient for the mail set in the envelope.
----
curl -v smtp://aspmx.l.google.com/smtp.example.com --mail-from Joedow@example.com --mail-rcpt yuri@yurisk.info --upload-file message.txt
----
.Here:
* `aspmx.l.google.com` - the mail server for the recipient domain (`curl` does NOT look for the MX record itself).
* `smtp.example.com` (Optional) - domain the `curl` will use in greeting the mail server (HELO/EHLO).
* `--mail-from` - sender address set in the envelope.
* `--mail-rcpt` - recipient for the mail set in the envelope.
NOTE: the mail sending is subject to all the anti-spam checks by the receiving mail server, so I recommend to run this with the `-v` option set to see what is going on in real-time.
<a name="ee17"></a>
### Make curl resolve a hostname to the custom IP address you specify without modifying hosts file or using DNS server hacks
== Make curl resolve a hostname to the custom IP address you specify without modifying hosts file or using DNS server hacks
Useful to test local copy of a website.
Problem: You want curl to reach a website "example.com" at IP address 127.0.0.1 without changing local `hosts` file or setting up fake DNS server.
Solution: Use `--resolve` to specify IP address for a hostname, so curl uses it without querying real DNS servers.
```Bash
----
curl -v --resolve "example.com:80:127.0.0.1" http://example.com
```
----
```Bash
----
* Added example.com:80:127.0.0.1 to DNS cache
* Hostname example.com was found in DNS cache
* Trying 127.0.0.1:80...
@@ -369,77 +335,82 @@ curl -v --resolve "example.com:80:127.0.0.1" http://example.com
> Host: example.com
> User-Agent: curl/7.67.0
> Accept: */*
```
----
<a name="ee18"></a>
### Show how many redirects were followed fetching the URL
== Show how many redirects were followed fetching the URL
Use `num_redirects` variable for that:
```Bash
----
curl -w '%{num_redirects}' -L -o /dev/null https://cnn.com -s
2
```
----
<a name="ee20"></a>
### Use your browser to prepare the complete curl command via "copy as curl" feature
== Use your browser to prepare the complete curl command via "copy as curl" feature
We can use a regular browser to prepare the complete curl command by just browsing to the target site. For that:
1. Open Developer Tools - **F12** (works in Chrome and Firefox)
2. Browse to the target site/page.
3. In the "Network" tab of the Developer Tools find the item you want to GET with curl, right click on it, find menu "Copy as cURL", click on it - this copies to the clipboard ready-to-run curl command to that asset.
. Open Developer Tools - **F12** (works in Chrome and Firefox)
. Browse to the target site/page.
. In the "Network" tab of the Developer Tools find the item you want to GET with curl, right click on it, find menu "Copy as cURL", click on it - this copies to the clipboard ready-to-run curl command to that asset.
<a name="ee21"></a>
### Test if a website supports the given cipher suite, e.g. obsolete sslv3 & DES
== Test if a website supports the given cipher suite, e.g. obsolete sslv3 & DES
Helps to monitor servers for obsolete or not yet widely supported cipher suites.
Check if site supports sslv3 (old and dangerously broken):
```Bash
----
curl -k https://yurisk.info:443 -v --sslv3
```
----
Output:
```Bash
----
curl: (35) error:1408F10B:SSL routines:ssl3_get_record:wrong version number
```
----
Check if the newest (experimental as of 2020) TLS v1.3 is enabled:
```Bash
----
curl -k https://yurisk.info:443 -v --tlsv1.3
```
----
Output:
```Bash
----
* OpenSSL SSL_connect: SSL_ERROR_ZERO_RETURN in connection to yurisk.info:443
* Marked for [closure]: Failed HTTPS connection
```
----
Check if a site supports easily breakable DES algorithm:
```Bash
----
curl -k -o /dev/null https://yurisk.info:443 --ciphers DES
```
----
Output:
```Bash
----
curl: (59) failed setting cipher list: DES
```
----
<a name="ee22"></a>
### Fetch multiple pages with predictable pattern in their URLs
== Fetch multiple pages with predictable pattern in their URLs
If a website has a repeating pattern in naming its resources, we can use **URL globbing**. curl understands ranges `[start-end]` and lists `{item1,item2,...}`. Ranges can be alphanumeric and are inclusive, i.e. [0-100] starts at 0 and includes up to 100. Ranges optionally accept step/increment value: `[10-100:2]`, here 2 is added on each step. We can use both, ranges and lists, in the same URL.
_Output files_: curl remembers the matched glob patterns and we can use them with `-o` to specify custom output filenames.
1. Fetch all pages in https://yurisk.info/category/checkpoint-ngngx<i>NNN</i>.html where _NNN_ goes from 2 to 9. Pay attention to the single quotes - when using on the Bash command line, the range `[]` and list `{}` operators would be otherwise interpreted by the Bash itself instead of curl.
```Bash
----
curl -s -O 'https://yurisk.info/category/checkpoint-ngngx[2-9].html'
```
----
Output directory:
```Bash
----
ls
checkpoint-ngngx2.html
checkpoint-ngngx3.html
@@ -449,50 +420,50 @@ checkpoint-ngngx6.html
checkpoint-ngngx7.html
checkpoint-ngngx8.html
checkpoint-ngngx9.html
```
----
2. Fetch all pages _cisco.html,fortinet.html,linux.html,checkpoint-ngngx.html_ inside the _category_ folder:
```bash
----
curl -O 'https://yurisk.info/category/{cisco,fortinet,linux,checkpoint-ngngx}.html'
```
----
Output:
```Bash
----
ls -1 *.html
checkpoint-ngngx.html
cisco.html
fortinet.html
linux.html
```
----
3. Download pages with alphabetical ranges.
```Bash
----
curl-O -s https://yurisk.info/test[a-z]
```
----
<a name="ee23"></a>
### How to prevent errors on URLs that contain brackets
== How to prevent errors on URLs that contain brackets
If the curl uses brackets (square and curly) for ranges (<a name="ee22">see above</a>), how do we work with URLs containing such symbols? By using the `-g` option to curl which turns off globbing. It also means we can't use ranges with URLs that contain brackets.
```bash
----
curl -g https://example.com/{ids}?site=example.gov
```
----
<a name="ee24"></a>
### Github: list names of all public repositories for a given user
To query the user's repositories, the URL should have the form of `https://api.github.com/users/<username>/repos `. For example, let's get all the repositories for `curl` project:
== Github: list names of all public repositories for a given user
To query the user's repositories, the URL should have the form of `https://api.github.com/users/<username>/repos`. For example, let's get all the repositories for `curl` project:
```bash
----
curl -s https://api.github.com/users/curl/repos | awk '/\wname/'
```
----
Output:
```bash
----
"full_name": "curl/build-images",
"full_name": "curl/curl",
"full_name": "curl/curl-cheat-sheet",
@@ -505,28 +476,27 @@ Output:
"full_name": "curl/fcurl",
"full_name": "curl/h2c",
"full_name": "curl/stats",
```
----
_Note:_ Github imposes rate limits on the unauthorized requests, currently 60 requests/hour is the maximum. You can check how many queries are left with the _X-Ratelimit-Remaining_ header:
```bash
----
curl -s -i https://api.github.com/users/curl/repos | grep X-Ratelimit-Remaining
X-Ratelimit-Remaining: 54`
```
----
<a name="ee26"></a>
### Display weather report for a given city
== Display weather report for a given city
There are many websites to query for weather information on the CLI, most popular seems to be wttr.in, so let's use it to get the weather in Milan:
```bash
----
curl wttr.in/Milan
```
----
Output:
```bash
----
Weather report: Milan
\ / Partly cloudy
@@ -555,9 +525,9 @@ Weather report: Milan
│ 0.0 mm | 0% │ 0.0 mm | 0% │ 0.0 mm | 0% │ 0.0 mm | 0% │
└──────────────────────────────┴──────────────────────────────┴──────────────────────────────┴──────────────────────────────┘
```
----
### References
== References
- Original post: https://yurisk.info/2020/03/13/curl-cookbook/