Man pages › Compared with Linux and the BSDs

`ssh-add(1)` on Solnix vs Linux and the BSDs

On a default Solnix system ssh-add is OpenSSH's ssh-add, from the openssh package in the base system. Its options match FreeBSD, Linux, NetBSD and OpenBSD except for -N, -P, -Q and the list of default key files.

The manual pages

Solnix: ssh-add(1) from pkgs.solnix.openssh
Linux: ssh-add(1) openssh-10.5p1
FreeBSD: ssh-add(1) 15.1-RELEASE
OpenBSD: ssh-add(1) 8.0
NetBSD: ssh-add(1) 11.0

What Solnix runs

The command on PATH is the OpenSSH ssh-add from the base system packages. No other variants are shipped. The Solnix page does not state which OpenSSH release it tracks; the Linux page is for openssh-10.5p1.

Differences

Compared with	Topic	What differs
Linux, OpenBSD, NetBSD	`-Q` (query agent extensions)	Linux, OpenBSD and NetBSD have ssh-add `-Q`, which asks the agent for the protocol extensions it supports. The Solnix synopsis and options list have no `-Q`, so a script using it will fail on Solnix. Source: Linux ssh-add(1) SYNOPSIS, -Q; OpenBSD ssh-add(1) -Q; NetBSD ssh-add(1) -Q; Solnix ssh-add(1) SYNOPSIS and OPTIONS
OpenBSD	`-P` (no PIN prompt)	OpenBSD has `-P`, which skips the PIN request when loading PKCS#11 or FIDO keys and fails if the token needs one. Solnix has no `-P`. Source: OpenBSD ssh-add(1) SYNOPSIS, -P; Solnix ssh-add(1) SYNOPSIS
FreeBSD	`-N` (certificate expiry)	Solnix has `-N`, which stops ssh-add asking the agent to delete a certificate shortly after its expiry date. The FreeBSD synopsis has no `-N`. Source: Solnix ssh-add(1) -N; FreeBSD ssh-add(1) SYNOPSIS
Linux, OpenBSD	default identity files	With no arguments, Linux and OpenBSD ssh-add also load ~/.ssh/id_mldsa44_ed25519. Solnix loads only id_rsa, id_ecdsa, id_ecdsa_sk, id_ed25519 and id_ed25519_sk, and so do FreeBSD and NetBSD. Source: Solnix ssh-add(1) DESCRIPTION; Linux ssh-add(1) DESCRIPTION; OpenBSD ssh-add(1) DESCRIPTION; FreeBSD ssh-add(1) DESCRIPTION; NetBSD ssh-add(1) DESCRIPTION
Linux, OpenBSD	default removal with `-d`	ssh-add `-d` with no arguments removes the default identities and their certificates. Because the default list differs, it covers id_mldsa44_ed25519 on Linux and OpenBSD but not on Solnix. Source: Solnix ssh-add(1) -d and DESCRIPTION; Linux ssh-add(1) -d and DESCRIPTION; OpenBSD ssh-add(1) -d and DESCRIPTION
Linux	same program	Linux and Solnix both document OpenSSH ssh-add. The documented options, including `-h` destination constraints, `-H`, `-E`, `-T`, `-s`, `-e`, `-K`, `-S`, `-t`, `-x` and `-X`, are the same apart from the `-Q` difference. Source: Solnix ssh-add(1) OPTIONS; Linux ssh-add(1) OPTIONS

Standards

POSIX: ssh-add is not a POSIX.1-2024 utility.

Writing portable scripts

Name key files explicitly instead of relying on ssh-add with no arguments. The default key list differs between systems.
Do not use -Q or -P in portable scripts. -Q is missing on Solnix and FreeBSD, and -P exists only on OpenBSD.

Every difference here is taken from the manual pages linked above: Solnix's published page, Linux (man-pages and the GNU and util-linux manuals), FreeBSD, OpenBSD and NetBSD. Each row names its source. Where a manual is silent, this page is too. Compiled 2026-10-26. Found a mistake? Mail hackers@lists.solnix.io.