podman-container-tools/podman · error

unable to print to string

Error message

unable to print to string

What it means

While creating the rootless pause process, the intermediate parent formats '<state_dir>/pause.pid.XXXXXX' with asprintf for an atomic (mkstemp + rename_noreplace) write of the pause PID (pkg/rootless/rootless_linux.c:1034-1039). This message means asprintf failed - i.e. ENOMEM - so the freshly forked pause child is SIGKILLed and the process _exits with failure, aborting the whole podman invocation before Go starts.

Source

Thrown at pkg/rootless/rootless_linux.c:1036

      int r, fd;

      close (p[0]);

      setsid ();
      pid = syscall_clone (SIGCHLD, NULL);
      if (pid < 0)
        _exit (EXIT_FAILURE);

      if (pid)
        {
          char pid_str[12];
          char *tmp_file_path = NULL;

          sprintf (pid_str, "%d", pid);

          if (asprintf (&tmp_file_path, "%s/pause.pid.XXXXXX", state_dir) < 0)
            {
              fprintf (stderr, "unable to print to string\n");
              kill (pid, SIGKILL);
              _exit (EXIT_FAILURE);
            }

          if (tmp_file_path == NULL)
            {
              fprintf (stderr, "temporary file path is NULL\n");
              kill (pid, SIGKILL);
              _exit (EXIT_FAILURE);
            }

          fd = mkstemp (tmp_file_path);
          if (fd < 0)
            {
              fprintf (stderr, "error creating temporary file: %m\n");
              kill (pid, SIGKILL);
              _exit (EXIT_FAILURE);
            }

View on GitHub (pinned to a2409076ef)

Solutions

1. Raise memory limits: 'ulimit -v unlimited' and check 'systemctl show user-$(id -u) -p MemoryMax'
2. Check 'dmesg' for OOM activity and free memory, then retry the command
3. Retry after the system load drops - the condition is transient
4. If it recurs with sane limits, report upstream with memory-limit details

# Guard memory limits before the first rootless podman command of a session
ulimit -v unlimited 2>/dev/null || true
free -m | awk 'NR==2 { if ($7 < 256) { print "low memory: " $7 " MiB free" > "/dev/stderr"; exit 1 } }'
podman "$@"

When it happens

Trigger: Memory exhaustion (RLIMIT_AS/cgroup cap/OOM) at the exact moment podman sets up the pause process for the user namespace - the only realistic cause of asprintf failing for this short string.

Common situations: Tight 'ulimit -v' or MemoryMax on user sessions; hosts under heavy memory pressure when starting rootless containers; first podman command in a session (when the pause process is created).

Related errors

• malloc: %m
• realloc buffer: %m
• save socket listen environments error: %m
• pause.pid file refers to PID %ld which is not a pause proces
• cannot retrieve cmd line

AI-assisted analysis of podman-container-tools/podman@a2409076ef (2026-08-15). Data as JSON: /api/errors/fb3e8235e5ef3dd0. Report an issue: GitHub.