podman-unshare(1)

💅 podman-unshare — from the podman fam, General Commands Manual vibes

okay bestie, pull up a chair because this one is genuinely iconic. podman-unshare runs a command inside a modified user namespace. yeah. we're doing namespace surgery and it slays.

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✨ NAME ✨

podman-unshare — run a command inside of a modified user namespace 🦋

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🌸 SYNOPSIS 🌸

podman unshare [options] [command]

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👑 DESCRIPTION 👑

so the tea is: this launches a process — by default, $SHELL — inside a new user namespace. and the namespace is configured so that your invoking user's UID and primary GID show up as UID 0 and GID 0 respectively. you're literally root in there. main character energy fr.

and any ranges that match that user and group in /etc/subuid and /etc/subgid also get mapped in as themselves, with a little help from the newuidmap(1) and newgidmap(1) helpers. teamwork makes the dream work 🫶

podman unshare is useful for troubleshooting unprivileged operations and for manually clearing storage and other data related to images and containers.

it's ALSO useful when you wanna use the podman mount command. like, if an unprivileged user wants to mount and work with a container, they need to execute podman unshare first. executing podman mount just fails for unprivileged users unless the user is already running inside a podman unshare session. no unshare, no mount, that's the rule 😭

the unshare session defines two environment variables, and they're both lowkey important:

• CONTAINERS_GRAPHROOT: the path to the persistent container's data.
• CONTAINERS_RUNROOT: the path to the volatile container's data.

⚠️ IMPORTANT: This command is not available with the remote Podman client. periodt.

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💖 OPTIONS 💖

--help, -h

Print usage statement. cute and simple, it just tells you how to use it ✨

--rootless-netns

Join the rootless network namespace used for netavark networking. it can be used to connect to a rootless container via IP address (bridge networking). this is otherwise not possible from the host network namespace. so basically: normally impossible, but with this flag? possible 💅

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🚦 Exit Codes 🚦

the exit code from podman unshare gives you information about why the container failed to run or why it exited. when podman unshare commands exit with a non-zero code, the exit codes follow the chroot standard, see below:

125 — The error is with podman itself

$ podman unshare --foo; echo $?
Error: unknown flag: --foo
125

126 — Executing a contained command and the command cannot be invoked

$ podman unshare /etc; echo $?
Error: fork/exec /etc: permission denied
126

127 — Executing a contained command and the command cannot be found

$ podman unshare foo; echo $?
Error: fork/exec /usr/bin/bogus: no such file or directory
127

Exit code contained command exit code — whatever the command you ran decided to exit with, you get that back

$ podman unshare /bin/sh -c 'exit 3'; echo $?
3

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🔥 EXAMPLE 🔥

Execute specified command in rootless user namespace:

$ podman unshare id
uid=0(root) gid=0(root) groups=0(root),65534(nobody)

Show user namespace mappings for rootless containers:

$ podman unshare cat /proc/self/uid_map /proc/self/gid_map
         0       1000          1
         1      10000      65536
         0       1000          1
         1      10000      65536

Show rootless netns information in user namespace for rootless containers:

$ podman unshare --rootless-netns ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: tap0: <BROADCAST,UP,LOWER_UP> mtu 65520 qdisc fq_codel state UNKNOWN group default qlen 1000
    link/ether aa:8c:0b:73:98:f6 brd ff:ff:ff:ff:ff:ff
    inet 10.0.2.100/24 brd 10.0.2.255 scope global tap0
       valid_lft forever preferred_lft forever
    inet6 fd00::a88c:bff:fe73:98f6/64 scope global dynamic mngtmpaddr
       valid_lft 86389sec preferred_lft 14389sec
    inet6 fe80::a88c:bff:fe73:98f6/64 scope link
       valid_lft forever preferred_lft forever

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🧚 SEE ALSO 🧚

podman(1), podman-mount(1), namespaces(7), newuidmap(1), newgidmap(1), user_namespaces(7)

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and that's the whole page, bestie — the podman-unshare(1) manual page itself, coming to you straight from the General Commands Manual. now go forth and unshare responsibly 💜🌈✨