write (system call)

<p>
The write is one of the most basic <a href="/facts/Subroutine/9vFJrg0A">routines</a> provided by a <a href="/facts/Unix-like/YAKrAxzd">Unix-like</a> <a href="/facts/Operating_system/8XTuvMh2">operating system</a> <a href="/facts/Kernel_(operating_system)/uEj4U3Rz">kernel</a>. It writes data from a buffer declared by the user to a given device, such as a file. This is the primary way to output data from a program by directly using a system call. The destination is identified by a <a href="/facts/File_descriptor/Iw74UKqG">numeric code</a>. The <a href="/facts/String_(computer_science)/4ChJu5WS">data</a> to be written, for instance a piece of text, is defined by a <a href="/facts/Pointer_(computer_programming)/fPoNzy9b">pointer</a> and a size, given in number of bytes.
</p><p>write thus takes three arguments:
</p>
<ol><li>The file code (<a href="/facts/File_descriptor/Iw74UKqG">file descriptor</a> or fd).</li>
<li>The pointer to a <a href="/facts/Data_buffer/tVy4j2Dc">buffer</a> where the data is stored (buf).</li>
<li>The number of bytes to write from the buffer (nbytes).</li></ol>

write (system call) open-in-new

write (system call)