putpwent(3)

✨ putpwent — bestie edition ✨

okay so this is putpwent(3), from the Library Functions Manual, and it's literally the "write a password file entry" girlie. tiny function, one job, zero drama. let's get into it 💖

---

🌸 NAME 🌸

putpwent — write a password file entry ✍️

---

📚 LIBRARY 📚

Standard C library (libc, link it with -lc) 🫶

---

🎀 SYNOPSIS 🎀

#include <stdio.h>
#include <sys/types.h>
#include <pwd.h>

int putpwent(const struct passwd *restrict p, FILE *restrict stream);

🦋 Feature Test Macro Requirements for glibc 🦋

(peep feature_test_macros(7) if you're new here)

putpwent():

• Since glibc 2.19:
  • _DEFAULT_SOURCE
• glibc 2.19 and earlier:
  • _SVID_SOURCE

not me having to remember which glibc era you're on before you can even call this 😭

---

💅 DESCRIPTION 💅

putpwent() writes a password entry — that's the struct p you handed it — into the file associated with stream. that's it. that's the whole function. iconic minimalism ✨

The passwd structure is defined in <pwd.h> like this, no cap:

struct passwd {
    char    *pw_name;        /* username */
    char    *pw_passwd;      /* user password */
    uid_t    pw_uid;         /* user ID */
    gid_t    pw_gid;         /* group ID */
    char    *pw_gecos;       /* real name */
    char    *pw_dir;         /* home directory */
    char    *pw_shell;       /* shell program */
};

every field is a whole vibe: pw_name is who you are, pw_passwd is the secret, pw_uid is your numeric main-character ID, pw_gid is your group, pw_gecos is your government name fr, pw_dir is where you live, pw_shell is what you run when you log in 🐚

---

🫶 RETURN VALUE 🫶

• 0 — slay, it worked, success 💖
• -1 — nope, it failed, and errno gets set to tell you why 🙈

---

💀 ERRORS 💀

• EINVAL — invalid (NULL) argument given. basically you passed it nothing and it said "girl what" 🚫

---

👑 ATTRIBUTES 👑

for what all these terms even mean, go read attributes(7), bestie.

• Interface: putpwent()
• Attribute: Thread safety
• Value: MT-Safe locale

MT-Safe locale, meaning the threading girlies can vibe, but watch your locale. noted. 💅

---

🌈 STANDARDS 🌈

None. literally none. it's giving "not standardized, we just live here" 😌

---

⭐ HISTORY ⭐

SVr4. vintage, but make it password-file ✨

---

🔥 SEE ALSO 🔥

endpwent(3), fgetpwent(3), getpw(3), getpwent(3), getpwnam(3), getpwuid(3), setpwent(3)

---

and that's the whole page, bestie!! this dropped in Linux man-pages 6.20, dated 2026-02-08, and yes the putpwent(3) energy is still immaculate. go write that password entry, you got this 💖🦋✨