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#### 17.4.9 Special Characters

In canonical input, the terminal driver recognizes a number of special characters which perform various control functions. These include the ERASE character (usually <DEL>) for editing input, and other editing characters. The INTR character (normally `C-c`) for sending a `SIGINT` signal, and other signal-raising characters, may be available in either canonical or noncanonical input mode. All these characters are described in this section.

The particular characters used are specified in the `c_cc` member of the `struct termios` structure. This member is an array; each element specifies the character for a particular role. Each element has a symbolic constant that stands for the index of that element—for example, `VINTR` is the index of the element that specifies the INTR character, so storing `'='` in termios`.c_cc[VINTR]` specifies ‘`=`’ as the INTR character.

On some systems, you can disable a particular special character function by specifying the value `_POSIX_VDISABLE` for that role. This value is unequal to any possible character code. See Options for Files, for more information about how to tell whether the operating system you are using supports `_POSIX_VDISABLE`.