The utmp file allows one to discover information about who is currently using the system. There may be more users currently using the system, because not all programs use utmp logging. Warning: utmp must not be writable

utmp, wtmp, btmp and variants such as utmpx, wtmpx and btmpx are files on Unix-like systems that keep track of all logins and logouts to the system. [1] These files are not regular text files, but rather a binary format which needs to be edited by specially crafted programs.

2023年11月17日 · utmp: It keeps track of currently logged-in users. wtmp: It keeps track of historical data of every log-in and logout activity. btmp: It maintains the record of invalid log-in attempts. Remember, these are the binary files and you can not use the cat command or open it in the text editor. They have different commands assigned for that purpose.

utmp 文 件 用 于 记 录 当 前 系 统 用 户 是 哪 些 人。 但 是 实 际 的 人 数 可 能 比 这 个 数 目 要 多 ， 因 为 并 非 所 有 用 户 都 用 utmp 登 录。 警告: utmp 必 须 置 为 不 可 写 ， 因 为 很 多 系 统 程 序 （ 有 点 傻 的 那 种 ） 依 赖 于 它。 如 果 你 将 它 置 为 可 写 ， 其 他 用 户 可 能 会 修 改 它 （//* 导 致 程 序 运 行 出 错 ） 。 （//* （//* ）中 为 译 者 注）

UNIX keeps track of who is currently logged into the system with a special file called utmp, or utmpx on Solaris systems. This is a binary file that contains a record for every active session and generally does not grow to be more than a few kilobytes in length. A second file, wtmpx, keeps a record of both logins and logouts.

The utmp file allows one to discover information about who is currently using UNIX. The file is a sequence of entries with the following structure declared in the include file: /* Copyright (C) 1993-2018 Free Software Foundation,

12.35 utmp.h ¶ Defines functions for login and logout (to a tty session) and for examining the history of logins and logouts. Documentation: https://www.gnu.org/software/libc/manual/html_node/Manipulating-the-Database.html, man utmp. Gnulib module: utmp-h Portability problems fixed by Gnulib:

utmpdump can be useful in cases of corrupted utmp or wtmp entries. It can dump out utmp/wtmp to an ASCII file, which can then be edited to remove bogus entries, and reintegrated using: utmpdump -r < ascii_file > wtmp But be warned, utmpdump was …

The getutmp() function copies the fields of the utmpx structure pointed to by ux to the corresponding fields of the utmp structure pointed to by u. The getutmpx () function performs the converse operation.

utmp, wtmp - login records. #include <utmp.h> The utmp file allows one to discover information about who is currently using the system. There may be more users currently using the system, because not all programs use utmp logging.