X509_NAME_PRINT_EX(3ossl)

💅 X509_NAME_PRINT_EX ✨ (3ossl)

okay bestie, welcome to the X509_NAME_PRINT_EX(3ossl) page, aka the OpenSSL manual where we talk about how to print out an X509_NAME — you know, the Distinguished Name situation, all those CN= and O= fields in your certs. it's giving "how do i make this look cute in a terminal" and honestly, we got options. so many options. 🎀

---

🌸 NAME 🌸

X509_NAME_print_ex, X509_NAME_print_ex_fp, X509_NAME_print, X509_NAME_oneline — the X509_NAME printing routines, aka your DN glow-up squad 💖

---

✨ SYNOPSIS ✨

#include <openssl/x509.h>

int X509_NAME_print_ex(BIO *out, const X509_NAME *nm,
                       int indent, unsigned long flags);
int X509_NAME_print_ex_fp(FILE *fp, const X509_NAME *nm,
                          int indent, unsigned long flags);
char *X509_NAME_oneline(const X509_NAME *a, char *buf, int size);
int X509_NAME_print(BIO *bp, const X509_NAME *name, int obase);

---

🦋 DESCRIPTION 🦋

X509_NAME_print_ex() prints a human readable version of nm to the BIO out. every line (for the multiline formats) gets indented by indent spaces, and you can customise the output extensively with the flags parameter. this is the main character fr 💅

X509_NAME_print_ex_fp() is literally identical to X509_NAME_print_ex() except the output goes to a FILE pointer fp instead. same energy, different destination 🌈

X509_NAME_oneline() prints an ASCII version of a to buf. it supports multi-valued RDNs and escapes / and + characters in values. and here's the tea: if buf is NULL, then a buffer is dynamically allocated and returned, and size is just ignored. otherwise, at most size bytes will be written — including the ending '\0' — and buf is returned. periodt. 👑

X509_NAME_print() prints out name to bp on a single line. the obase parameter is ignored and retained only for API compatibility. it's just there vibing, contributing nothing 🙈

---

🔥 NOTES 🔥

okay so, real talk: the functions X509_NAME_oneline() and X509_NAME_print() produce a non standard output form. they don't handle multi-character fields and they have various quirks and inconsistencies. their use is strongly discouraged in new applications and they could be deprecated in a future release. bestie, don't build your new thing on these, i'm begging 😭

although there are a large number of possible flags, for most purposes XN_FLAG_ONELINE, XN_FLAG_MULTILINE or XN_FLAG_RFC2253 will suffice. and as noted on the ASN1_STRING_print_ex(3) manual page, for UTF8 terminals the ASN1_STRFLGS_ESC_MSB should be unset: so for example XN_FLAG_ONELINE & ~ASN1_STRFLGS_ESC_MSB would be used. lowkey a little combo move 💫

the complete set of the flags supported by X509_NAME_print_ex() is listed below. several options can be ored together — mix and match, it's a build-your-own-format situation ✨

• XN_FLAG_SEP_COMMA_PLUS, XN_FLAG_SEP_CPLUS_SPC, XN_FLAG_SEP_SPLUS_SPC and XN_FLAG_SEP_MULTILINE — these determine the field separators to use. two distinct separators get used: one between distinct RelativeDistinguishedName components, and one to separate values in the same RDN for a multi-valued RDN. multi-valued RDNs are currently very rare so that second separator will hardly ever be used. it's giving "invited to the party but never shows up" 💀
  • XN_FLAG_SEP_COMMA_PLUS uses comma and plus as separators.
  • XN_FLAG_SEP_CPLUS_SPC uses comma and plus with spaces: this is more readable that plain comma and plus.
  • XN_FLAG_SEP_SPLUS_SPC uses spaced semicolon and plus.
  • XN_FLAG_SEP_MULTILINE uses spaced newline and plus respectively.
• XN_FLAG_DN_REV — if set, the whole DN is printed in reversed order. backwards but make it fashion 🔄
• XN_FLAG_FN_SN, XN_FLAG_FN_LN, XN_FLAG_FN_OID, XN_FLAG_FN_NONE — these determine how a field name is displayed. respectively they make it use the short name (e.g. CN), the long name (e.g. commonName), always use OID numerical form (normally OIDs are only used if the field name is not recognised), and no field name at all. pick your vibe 🎀
• XN_FLAG_SPC_EQ — if set, then spaces will be placed around the '=' character separating field names and values. breathing room, we love to see it 🌸
• XN_FLAG_DUMP_UNKNOWN_FIELDS — if set, then the encoding of unknown fields is printed instead of the values. mystery field? we show the receipts 🔍
• XN_FLAG_FN_ALIGN — if set, then field names are padded to 20 characters: this is only of use for multiline format. alignment is self-care, ngl 🫶

additionally, all the options supported by ASN1_STRING_print_ex() can be used to control how each field value is displayed. 👑

in addition, a number options can be set for commonly used formats — these are the presets, the ready-to-wear of DN printing:

• XN_FLAG_RFC2253 sets options which produce an output compatible with RFC2253. it is equivalent to:

"ASN1_STRFLGS_RFC2253 | XN_FLAG_SEP_COMMA_PLUS | XN_FLAG_DN_REV
  | XN_FLAG_FN_SN | XN_FLAG_DUMP_UNKNOWN_FIELDS"

• XN_FLAG_ONELINE is a more readable one line format which is the same as:

"ASN1_STRFLGS_RFC2253 | ASN1_STRFLGS_ESC_QUOTE | XN_FLAG_SEP_CPLUS_SPC
  | XN_FLAG_SPC_EQ | XN_FLAG_FN_SN"

• XN_FLAG_MULTILINE is a multiline format which is the same as:

"ASN1_STRFLGS_ESC_CTRL | ASN1_STRFLGS_ESC_MSB | XN_FLAG_SEP_MULTILINE
  | XN_FLAG_SPC_EQ | XN_FLAG_FN_LN | XN_FLAG_FN_ALIGN"

• XN_FLAG_COMPAT uses a format identical to X509_NAME_print(): in fact it calls X509_NAME_print() internally. it's giving "no thoughts, just delegate" 💅

---

⭐ RETURN VALUES ⭐

• X509_NAME_oneline() returns a valid string on success or NULL on error. 🎀
• X509_NAME_print() returns 1 on success or 0 on error.
• X509_NAME_print_ex() and X509_NAME_print_ex_fp() return 1 on success or 0 on error if the XN_FLAG_COMPAT is set, which is the same as X509_NAME_print(). otherwise, it returns -1 on error or other values on success. yeah bestie, the return contract literally changes based on a flag, that's just how it is 😭

---

🌈 SEE ALSO 🌈

ASN1_STRING_print_ex(3) — go read that one too, it's the sibling page and it's important for the flags situation 💜

---

👑 COPYRIGHT 👑

Copyright 2002-2026 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.

---

and that's the whole page, bestie 💖 this was version 3.5.9, dated 2026-09-29, straight from the OpenSSL squad. now go print some names and slay ✨🦋🎀