[curl] Check to see if cURL is installed locally?

How do I check if cURL is installed on my local server instance?

Does it matter what type of server I'm running to check it?

Is it different if it's a PHP server or a CF server?

Assuming you want curl installed: just execute the install command and see what happens.

$ sudo yum install curl

Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.cat.pdx.edu
 * epel: mirrors.kernel.org
 * extras: mirrors.cat.pdx.edu
 * remi-php72: repo1.sea.innoscale.net
 * remi-safe: repo1.sea.innoscale.net
 * updates: mirrors.cat.pdx.edu
Package curl-7.29.0-54.el7_7.1.x86_64 already installed and latest version
Nothing to do

To extend the answer above and if the case is you are using XAMPP. In the current version of the xampp you cannot locate the curl_exec in the php.ini, just try using

<?php
echo '<pre>';
var_dump(curl_version());
echo '</pre>';
?>

and save to your htdocs. Next go to your browser and paste

http://localhost/[your_filename].php

if the result looks like this

array(9) {
  ["version_number"]=>
  int(469760)
  ["age"]=>
  int(3)
  ["features"]=>
  int(266141)
  ["ssl_version_number"]=>
  int(0)
  ["version"]=>
  string(6) "7.43.0"
  ["host"]=>
  string(13) "i386-pc-win32"
  ["ssl_version"]=>
  string(14) "OpenSSL/1.0.2e"
  ["libz_version"]=>
  string(5) "1.2.8"
  ["protocols"]=>
  array(19) {
    [0]=>
    string(4) "dict"
    [1]=>
    string(4) "file"
    [2]=>
    string(3) "ftp"
    [3]=>
    string(4) "ftps"
    [4]=>
    string(6) "gopher"
    [5]=>
    string(4) "http"
    [6]=>
    string(5) "https"
    [7]=>
    string(4) "imap"
    [8]=>
    string(5) "imaps"
    [9]=>
    string(4) "ldap"
    [10]=>
    string(4) "pop3"
    [11]=>
    string(5) "pop3s"
    [12]=>
    string(4) "rtsp"
    [13]=>
    string(3) "scp"
    [14]=>
    string(4) "sftp"
    [15]=>
    string(4) "smtp"
    [16]=>
    string(5) "smtps"
    [17]=>
    string(6) "telnet"
    [18]=>
    string(4) "tftp"
  }
}

curl is enable

cURL is disabled for most hosting control panels for security reasons, but it's required for a lot of php applications. It's not unusual for a client to request it. Since the risk of enabling cURL is minimal, you are probably better off enabling it than losing a customer. It's simply a utility that helps php scripts fetch things using standard Internet URLs.

To enable cURL, you will remove curl_exec from the "disabled list" in the control panel php advanced settings. You will also find a disabled list in the various php.ini files; look in /etc/php.ini and other paths that might exist for your control panel. You will need to restart Apache to make the change take effect.

service httpd restart

To confirm whether cURL is enabled or disabled, create a file somewhere in your system and paste the following contents.

<?php
echo '<pre>';
var_dump(curl_version());
echo '</pre>';
?>

Save the file as testcurl.php and then run it as a php script.

php testcurl.php

If cURL is disabled you will see this error.

Fatal error: Call to undefined function curl_version() in testcurl.php on line 2

If cURL is enabled you will see a long list of attributes, like this.

array(9) {
["version_number"]=>
int(461570)
["age"]=>
int(1)
["features"]=>
int(540)
["ssl_version_number"]=>
int(9465919)
["version"]=>
string(6) "7.11.2"
["host"]=>
string(13) "i386-pc-win32"
["ssl_version"]=>
string(15) " OpenSSL/0.9.7c"
["libz_version"]=>
string(5) "1.1.4"
["protocols"]=>
array(9) {
[0]=>
string(3) "ftp"
[1]=>
string(6) "gopher"
[2]=>
string(6) "telnet"
[3]=>
string(4) "dict"
[4]=>
string(4) "ldap"
[5]=>
string(4) "http"
[6]=>
string(4) "file"
[7]=>
string(5) "https"
[8]=>
string(4) "ftps"
}
}

Another way, say in CentOS, is:

$ yum list installed '*curl*'
Loaded plugins: aliases, changelog, fastestmirror, kabi, langpacks, priorities, tmprepo, verify,
              : versionlock
Loading support for Red Hat kernel ABI
Determining fastest mirrors
google-chrome                                                                                    3/3
152 packages excluded due to repository priority protections
Installed Packages
curl.x86_64                                        7.29.0-42.el7                                @base
libcurl.x86_64                                     7.29.0-42.el7                                @base
libcurl-devel.x86_64                               7.29.0-42.el7                                @base
python-pycurl.x86_64                               7.19.0-19.el7                                @base