This is a Command Line icon. We've made it in iOS style, first introduced in iOS version 7 and supported in all later releases up until now (at least iOS 11). This style is based on thin two-pixel lines and is optimized for 50x50 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 12,700 icons, all in the same style and quality.
This is a command line symbol from the Microsoft Windows Operating system. There is a rectangle with a line horizontally through the top to create a header look. Inside the rectangle is the letter C followed by a semi colon and then a forward slash.