UTIMES(2)

💖 utimes(2) — the file-time glow-up manual 💖

okay so bestie, you opened the utimes(2) page and we are about to make timestamp lore make sense. no cap, this one is all about setting access and modification times, and there are a few variants that are lowkey doing their own little thing. let's go. ✨

🌸 NAME 🌸

utimes, lutimes, futimes, futimesat — set file access and modification times. periodt. 💅

🎀 LIBRARY 🎀

Standard C Library (libc, -lc) — yes bestie, the libc girlies are carrying this.

✨ SYNOPSIS ✨

#include <sys/time.h>

int
utimes(const char *path, const struct timeval *times);

int
lutimes(const char *path, const struct timeval *times);

int
futimes(int fd, const struct timeval *times);

int
futimesat(int fd, const char *path, const struct timeval times[2]);

💅 DESCRIPTION 💅

okay so first thing: these interfaces are obsoleted by futimens(2) and utimensat(2) because they are not accurate to nanoseconds. fr fr, that's the whole vibe check — they're the older timestamp girlies.

The access and modification times of the file named by path or referenced by fd are changed as specified by the argument times.

If times is NULL, the access and modification times are set to the current time. The caller must be the owner of the file, have permission to write the file, or be the super-user. literally the rules, bestie.

If times is non-NULL, it is assumed to point to an array of two timeval structures. The access time is set to the value of the first element, and the modification time is set to the value of the second element. For file systems that support file birth (creation) times (such as UFS2), the birth time will be set to the value of the second element if the second element is older than the currently set birth time. To set both a birth time and a modification time, two calls are required; the first to set the birth time and the second to set the (presumably newer) modification time. Ideally a new system call will be added that allows the setting of all three times at once. The caller must be the owner of the file or be the super-user.

In either case, the inode-change-time of the file is set to the current time. iconic behavior, honestly.

The lutimes() system call is like utimes() except in the case where the named file is a symbolic link, in which case lutimes() changes the access and modification times of the link, while utimes() changes the times of the file the link references. it's giving "look at the link itself, not the target" 💅

The futimesat() system call is equivalent to utimes() except in the case where path specifies a relative path. In this case the access and modification time is set to that of a file relative to the directory associated with the file descriptor fd instead of the current working directory. If futimesat() is passed the special value AT_FDCWD in the fd parameter, the current working directory is used and the behavior is identical to a call to utimes(). iykyk 🫶

🫶 RETURN VALUES 🫶

Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error. simple as that, bestie — 0 is the slay, -1 is the "check errno" moment. 😭

💀 ERRORS 💀

All of the system calls will fail if:

• EACCES — Search permission is denied for a component of the path prefix.
• EACCES — The times argument is NULL and the effective user ID of the process does not match the owner of the file, and is not the super-user, and write access is denied.
• EFAULT — The path or times argument points outside the process's allocated address space.
• EFAULT — The times argument points outside the process's allocated address space.
• EINVAL — The tv_usec component of at least one of the values specified by the times argument has a value less than 0 or greater than 999999.
• EIO — An I/O error occurred while reading or writing the affected inode.
• EINTEGRITY — Corrupted data was detected while reading from the file system.
• ELOOP — Too many symbolic links were encountered in translating the pathname.
• ENAMETOOLONG — A component of a pathname exceeded NAME_MAX characters, or an entire path name exceeded PATH_MAX characters.
• ENOENT — The named file does not exist.
• ENOTDIR — A component of the path prefix is not a directory.
• EPERM — The times argument is not NULL and the calling process's effective user ID does not match the owner of the file and is not the super-user.
• EPERM — The named file has its immutable or append-only flags set. See the chflags(2) manual page for more information.
• EROFS — The file system containing the file is mounted read-only.

The futimes() system call will fail if:

• EBADF — The fd argument does not refer to a valid descriptor.

In addition to the errors returned by the utimes(), the futimesat() may fail if:

• EBADF — The path argument does not specify an absolute path and the fd argument is neither AT_FDCWD nor a valid file descriptor open for searching.
• ENOTDIR — The path argument is not an absolute path and fd is neither AT_FDCWD nor a file descriptor associated with a directory.

bestie, these error lists are not a vibe — read them carefully, especially the duplicate EACCES, EFAULT, and EPERM entries. they are separate conditions, not a typo. 💀

🔗 SEE ALSO 🔗

chflags(2), stat(2), utimensat(2), utime(3)

📜 STANDARDS 📜

The utimes() function is expected to conform to X/Open Portability Guide Issue 4, Version 2 (“XPG4.2”). The futimesat() system call follows The Open Group Extended API Set 2 specification but was replaced by utimensat() in IEEE Std 1003.1-2008 (“POSIX.1”).

🦋 HISTORY 🦋

The utimes() system call appeared in 4.2BSD. The futimes() and lutimes() system calls first appeared in FreeBSD 3.0. The futimesat() system call appeared in FreeBSD 8.0.

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💖 source/version: Debian build · date: March 30, 2020 · that's the utimes(2) manual, bestie — now go set those timestamps, mwah 💖