Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
read (system call)
open-in-new
<p>In modern <a href="/facts/POSIX/mQkSt234">POSIX</a> compliant <a href="/facts/Operating_systems/8XTuvMh2">operating systems</a>, a program that needs to access data from a <a href="/facts/Computer_file/FjFH3Ufm">file</a> stored in a <a href="/facts/File_system/FdPm90uc">file system</a> uses the read system call. The file is identified by a <a href="/facts/File_descriptor/Iw74UKqG">file descriptor</a> that is normally obtained from a previous call to <a href="/facts/Open_(system_call)/TP39FgXh">open</a>. This system call reads in data in <a href="/facts/Byte/BNHUp9Qq">bytes</a>, the number of which is specified by the caller, from the file and stores then into a buffer supplied by the calling process. </p><p>The read system call takes three arguments: </p> <ol><li>The file descriptor of the file.</li> <li>The buffer where the read data is to be stored.</li> <li>The number of bytes to be read from the file.</li></ol>