The curl
command is a powerful tool for transferring data over the internet. In this blog post, we’ll explore some of the many ways that you can use curl
in your Bash scripts and command-line workflows.
Downloading Files
One of the most common uses for curl
is to download files from the internet. To download a file, simply pass the URL of the file to curl
. For example, to download the latest version of the Ubuntu ISO file, you can use the following command:
curl -O <http://releases.ubuntu.com/20.04/ubuntu-20.04-desktop-amd64.iso>
The -O
flag tells curl
to save the file with the same name as it has on the server.
You can also specify a different name for the downloaded file by including the desired filename as the last argument.
curl -o new_name.txt <https://www.example.com/example.txt>
Uploading Files
curl
can also be used to upload files to a server. To do this, use the -F
flag followed by the name of the file to upload. For example:
curl -F "file=@/path/to/local_file.txt" <https://www.example.com/upload>
You can also use curl
to upload multiple files at once.
curl -F "file1=@/path/to/local_file1.txt" -F "file2=@/path/to/local_file2.txt" <https://www.example.com/upload>
HTTP Requests
curl
can also be used to make HTTP requests, including GET, POST, PUT, and DELETE requests.
For example, to send a GET request to a website:
curl <https://www.example.com>
To send a POST request with data:
curl -X POST -d "name=value" <https://www.example.com/form>
or you can use JSON
curl -X POST -H "Content-Type: application/json" -d '{"key":"value"}' <https://www.example.com/data>
You can also use curl
to make authenticated requests. For example, to make a request with a basic authentication:
curl --user username:password <https://www.example.com>
Other features
curl
also has a variety of other features that can be useful in certain situations.
For example, you can use the -L
flag to follow redirects, and the -v
flag to print verbose output, including the headers sent and received.
Additionally, curl
supports the use of various protocols such as FTP, SFTP, HTTP, HTTPS, SCP, and many more.
curl <ftp://ftp.example.com>
curl sftp://user:password@example.com
Piping Curl With Other Commands
It’s also worth noting that curl
can be used in conjunction with other command-line tools, such as awk
, grep
, and sed
, to further manipulate and process the data returned by curl
.
For example, you can use awk
to extract specific data from the response, grep
to search for specific patterns, or sed
to replace text in the response.
curl <https://www.example.com> | awk '{print $2}'
curl <https://www.example.com> | grep "example"
curl <https://www.example.com> | sed "s/example/new_example/g"
In summary, curl
is an essential command-line tool for any power user or advanced user working with data on the internet. With its simple syntax and powerful features, curl
can help you automate your workflows, streamline your process, and extract valuable insights from data on the internet.