SETARCH(8)

💖 SETARCH(8) 💖

okay bestie, welcome to setarch — it's a System Administration page, section 8, and it's lowkey one of the most underrated glow-ups in the util-linux lineup. sit down, hydrate, let's get into it ✨

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✨ NAME ✨

setarch — change the reported architecture in a new program's environment, and/or mess with its personality flags 🦋

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🌸 SYNOPSIS 🌸

setarch [arch] [options] [program [argument...]]

arch [options] [program [argument...]]

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👑 DESCRIPTION 👑

So setarch does two things: it tweaks the execution domain and the process personality flags. That's the whole vibe.

The execution domain, rn, only affects what uname -m spits out. Like, picture an AMD64 machine — if you run setarch i386 program, then program will look around and see i686 instead of x86_64 as the machine type. gaslighting, but make it kernel-level 💅

The default program, if you don't hand it one, is /bin/sh.

And here's the glow-up: since version 2.33, the arch command-line argument is optional. Which means you can use setarch purely to flip personality flags (ADDR_LIMIT_3GB, SHORT_INODE, etc) without touching the execution domain at all. main character energy, honestly 👑

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💅 OPTIONS 💅

• --list — lists all the architectures setarch knows about. ngl tho, whether it can actually set each one depends on your running kernel. so it's giving "here's the menu, kitchen may vary" 🍓
• --show[=personality] — shows the personality and flags that are active right now. if you pass the personality argument, it shows that personality instead of the current one. personality is a hexadecimal number, and the possible values live in sys/personality.h. go read it, it's a whole mood.
• -p, --pid=pid — when you use this alongside --show, it'll show the personality and flags of the process you specify. nosy in the best way 🙈
• --uname-2.6 — makes the specified program see a kernel version number starting with 2.6. turns on UNAME26. blast from the past fr fr.
• -v, --verbose — be verbose. say more. spill ☕
• -3, --3gb — the specified program should cap itself at a maximum of 3GB of address space. supported on x86. turns on ADDR_LIMIT_3GB.
• --4gb — this option does nothing. it's hanging around purely for backward compatibility, and it may get yeeted in future releases. 💀
• -B, --32bit — limits the address space to 32 bits to emulate hardware. supported on ARM and Alpha. turns on ADDR_LIMIT_32BIT.
• -F, --fdpic-funcptrs — treats user-space function pointers to signal handlers as pointers to address descriptors. this one has no effect on architectures that don't support FDPIC ELF binaries. and heads up: in kernel v4.14, support is limited to ARM, Blackfin, Fujitsu FR-V, and SuperH CPU architectures.
• -I, --short-inode — obsolete bug emulation flag. turns on SHORT_INODE. vintage, but not in a cute way.
• -L, --addr-compat-layout — gives you the legacy virtual address space layout. use it when the program binary doesn't have a PT_GNU_STACK ELF header. turns on ADDR_COMPAT_LAYOUT.
• -R, --addr-no-randomize — disables randomization of the virtual address space. turns on ADDR_NO_RANDOMIZE. chaos off 🎀
• -S, --whole-seconds — another obsolete bug emulation flag. turns on WHOLE_SECONDS.
• -T, --sticky-timeouts — this makes the select(2), pselect(2), and ppoll(2) system calls preserve the timeout value instead of modifying it to reflect how much time wasn't slept when a signal handler interrupted it. use this when your program depends on that behavior. for more deets, see the timeout description in the select(2) manual page. turns on STICKY_TIMEOUTS.
• -X, --read-implies-exec — if this is set, then mmap(2) with PROT_READ will also add the PROT_EXEC bit — exactly what legacy x86 binaries expect. but notice: the ELF loader will automatically set this bit when it runs into a legacy binary anyway. turns on READ_IMPLIES_EXEC.
• -Z, --mmap-page-zero — SVr4 bug emulation that sets mmap(2) page zero as read-only. use it when your program depends on this behavior and you don't have the source code to fix it. turns on MMAP_PAGE_ZERO.
• -h, --help — display help text and exit. the classic escape hatch 🫶
• -V, --version — display version and exit.

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🌈 EXAMPLES 🌈

these are literally copy-paste ready, bestie:

setarch --addr-no-randomize mytestprog
setarch ppc32 rpmbuild --target=ppc --rebuild foo.src.rpm
setarch ppc32 -vL3 rpmbuild --target=ppc --rebuild bar.src.rpm
setarch ppc32 --32bit rpmbuild --target=ppc --rebuild foo.src.rpm
setarch --show
setarch --show=$(cat /proc/9284/personality)
setarch --show --pid 9284

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🧚 AUTHORS 🧚

Elliot Lee <sopwith@redhat.com>, Jindrich Novy <jnovy@redhat.com>, Karel Zak <kzak@redhat.com> — icons, all three of them 👑

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🔥 SEE ALSO 🔥

personality(2), select(2) *proc_pid_personality(5)

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🎀 REPORTING BUGS 🎀

found a bug? don't suffer in silence, bestie. use the issue tracker at <https://github.com/util-linux/util-linux/issues>. they want to hear it, fr fr.

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⭐ AVAILABILITY ⭐

The setarch command is part of the util-linux package, which you can download from the Linux Kernel Archive at <https://www.kernel.org/pub/linux/utils/util-linux/>. go get your girl 💜

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okay that's the whole page!! this is util-linux 2.42.4, dated 2026-09-21, and yes this is SETARCH(8) signing off. slay, stay safe, and remember: your personality flags are yours to choose 🦋✨