diff --git a/README.md b/README.md
index a26218b..1966f2a 100644
--- a/README.md
+++ b/README.md
@@ -136,8 +136,9 @@ The following lists the options:
     Specify multiple times for more than one path to mount.
 
 -n, --hostname-pattern <pattern>
-    Specify a hostname for the system. The pattern is a printf(3)
-    pattern. It is passed a unique ID for the board. E.g., "nerves-%.4s"
+    Specify a hostname for the system. The pattern supports a "%[-][.len]s"
+    where len is the length of the unique ID to use and the "-" controls
+    whether the ID is trimmed from the right or left. E.g., "nerves-%.4s"
 
 --pre-run-exec <program and arguments>
     Run the specified command before Erlang starts
@@ -201,7 +202,7 @@ The following lists the options:
 ```
 
 If you're using this in combination with `Nerves` you can customize configration
-via the application env as well. For details see the 
+via the application env as well. For details see the
 [related documentation](https://hexdocs.pm/nerves/advanced-configuration.html#overriding-erlinit-config-from-mix-config).
 
 ## Rebooting or hanging when the Erlang VM exits
diff --git a/src/hostname.c b/src/hostname.c
index a5efc09..3ecf2bb 100644
--- a/src/hostname.c
+++ b/src/hostname.c
@@ -83,6 +83,63 @@ static void make_rfc1123_compatible(char *s)
     *d = '\0';
 }
 
+static inline int digit2int(char digit)
+{
+    return digit - '0';
+}
+
+static inline int min(int a, int b)
+{
+    if (a < b)
+        return a;
+    else
+        return b;
+}
+
+static void hostname_sprintf(char *output, const char *pattern, const char *serial)
+{
+    // Simple version of sprintf that supports a subset of patterns:
+    //   %s        - Include the whole string
+    //   %.<len>s  - Include len characters of the string starting at the left
+    //   %-.<len>s - Include len characters of the string starting at the right
+    while (*pattern) {
+        if (*pattern == '%') {
+            pattern++;
+            const char *start = serial;
+            int max_len = strlen(serial);
+            int len;
+            if (pattern[0] == 's') {
+                pattern++;
+                len = max_len;
+            } else if (pattern[0] == '.' && isdigit(pattern[1]) && pattern[2] == 's') {
+                len = min(max_len, digit2int(pattern[1]));
+                pattern += 3;
+            } else if (pattern[0] == '.' && isdigit(pattern[1]) && isdigit(pattern[2]) && pattern[3] == 's') {
+                len = min(max_len, digit2int(pattern[1]) * 10 + digit2int(pattern[2]));
+                pattern += 4;
+            } else if (pattern[0] == '-' && pattern[1] == '.' && isdigit(pattern[2]) && pattern[3] == 's') {
+                len = min(max_len, digit2int(pattern[2]));
+                start += max_len - len;
+                pattern += 4;
+            } else if (pattern[0] == '-' && pattern[1] == '.' && isdigit(pattern[2]) && isdigit(pattern[3]) && pattern[4] == 's') {
+                len = min(max_len, digit2int(pattern[2]) * 10 + digit2int(pattern[3]));
+                start += max_len - len;
+                pattern += 5;
+            } else {
+                // Just give up on bad percent escapes. The config file is wrong and
+                // hopefully it will be obvious that the pattern was broke. Don't crash
+                // or error, since this shouldn't mess up booting.
+                break;
+            }
+            memcpy(output, start, len);
+            output += len;
+        } else {
+            *output++ = *pattern++;
+        }
+    }
+    *output = '\0';
+}
+
 void configure_hostname()
 {
     debug("configure_hostname");
@@ -101,7 +158,7 @@ void configure_hostname()
                 warn("`%s` failed. Using default ID: '%s'", options.uniqueid_exec, unique_id);
             }
         }
-        sprintf(hostname, options.hostname_pattern, unique_id);
+        hostname_sprintf(hostname, options.hostname_pattern, unique_id);
         kill_whitespace(hostname);
         make_rfc1123_compatible(hostname);
     } else {
diff --git a/tests/010_uniqueid b/tests/010_uniqueid
index 3671abd..aed3999 100644
--- a/tests/010_uniqueid
+++ b/tests/010_uniqueid
@@ -17,7 +17,7 @@ EOF
 cat >"$WORK/usr/bin/make-unique-id" <<EOF
 #!/usr/bin/env bash
 
-echo "0042"
+echo "12345678"
 EOF
 chmod +x "$WORK/usr/bin/make-unique-id"
 
@@ -54,8 +54,8 @@ fixture: ioctl(SIOCSIFFLAGS)
 fixture: ioctl(SIOCGIFINDEX)
 erlinit: configure_hostname
 erlinit: system_cmd '/usr/bin/make-unique-id'
-erlinit: Hostname: nerves-0042
-fixture: sethostname("nerves-0042", 11)
+erlinit: Hostname: nerves-1234
+fixture: sethostname("nerves-1234", 11)
 fixture: mkdir("/root/seedrng", 700)
 erlinit: Saving 256 bits of creditable seed for next boot
 erlinit: Env: 'HOME=/home/user0'
diff --git a/tests/061_uniqueid_full b/tests/061_uniqueid_full
new file mode 100644
index 0000000..1f5f8c3
--- /dev/null
+++ b/tests/061_uniqueid_full
@@ -0,0 +1,96 @@
+#!/usr/bin/env bash
+
+#
+# Test that calling out to a unique id generator does the right thing
+#
+
+cat >"$CONFIG" <<EOF
+-v
+
+# Specify a hostname pattern that has a unique id part
+--hostname-pattern nerves-%s-
+
+# Call out to a dummy unique id generator
+--uniqueid-exec "/usr/bin/make-unique-id"
+EOF
+
+cat >"$WORK/usr/bin/make-unique-id" <<EOF
+#!/usr/bin/env bash
+
+echo "12345678"
+EOF
+chmod +x "$WORK/usr/bin/make-unique-id"
+
+cat >"$EXPECTED" <<EOF
+erlinit: cmdline argc=1, merged argc=6
+erlinit: merged argv[0]=/sbin/init
+erlinit: merged argv[1]=-v
+erlinit: merged argv[2]=--hostname-pattern
+erlinit: merged argv[3]=nerves-%s-
+erlinit: merged argv[4]=--uniqueid-exec
+erlinit: merged argv[5]=/usr/bin/make-unique-id
+fixture: mount("proc", "/proc", "proc", 14, data)
+fixture: mount("sysfs", "/sys", "sysfs", 14, data)
+fixture: mount("devtmpfs", "/dev", "devtmpfs", 42, data)
+fixture: mkdir("/dev/pts", 755)
+fixture: mkdir("/dev/shm", 1777)
+fixture: mount("devpts", "/dev/pts", "devpts", 10, data)
+fixture: symlink("/dev/mmcblk0","/dev/rootdisk0")
+fixture: symlink("/dev/mmcblk0p4","/dev/rootdisk0p4")
+fixture: symlink("/dev/mmcblk0p3","/dev/rootdisk0p3")
+fixture: symlink("/dev/mmcblk0p2","/dev/rootdisk0p2")
+fixture: symlink("/dev/mmcblk0p1","/dev/rootdisk0p1")
+erlinit: set_ctty
+fixture: setsid()
+fixture: mount("tmpfs", "/tmp", "tmpfs", 14, data)
+fixture: mount("tmpfs", "/run", "tmpfs", 14, data)
+erlinit: find_release
+erlinit: No release found in /srv/erlang.
+erlinit: find_erts_directory
+erlinit: setup_environment
+erlinit: setup_networking
+fixture: ioctl(SIOCGIFFLAGS)
+fixture: ioctl(SIOCSIFFLAGS)
+fixture: ioctl(SIOCGIFINDEX)
+erlinit: configure_hostname
+erlinit: system_cmd '/usr/bin/make-unique-id'
+erlinit: Hostname: nerves-12345678-
+fixture: sethostname("nerves-12345678-", 16)
+fixture: mkdir("/root/seedrng", 700)
+erlinit: Saving 256 bits of creditable seed for next boot
+erlinit: Env: 'HOME=/home/user0'
+erlinit: Env: 'PATH=/usr/sbin:/usr/bin:/sbin:/bin'
+erlinit: Env: 'TERM=xterm-256color'
+erlinit: Env: 'ROOTDIR=/usr/lib/erlang'
+erlinit: Env: 'BINDIR=/usr/lib/erlang/erts-6.0/bin'
+erlinit: Env: 'EMU=beam'
+erlinit: Env: 'PROGNAME=erlexec'
+erlinit: Arg: 'erlexec'
+erlinit: Arg: '-boot_var'
+erlinit: Arg: 'RELEASE_LIB'
+erlinit: Arg: '/srv/erlang/lib'
+erlinit: Launching erl...
+Hello from erlexec
+erlinit: Erlang VM exited
+erlinit: kill_all
+erlinit: Sending SIGTERM to all processes
+fixture: kill(-1, 15)
+fixture: sleep(1)
+erlinit: Sending SIGKILL to all processes
+fixture: kill(-1, 9)
+fixture: mkdir("/root/seedrng", 700)
+erlinit: Seeding 256 bits and crediting
+fixture: ioctl(RNDADDENTROPY)
+erlinit: Saving 256 bits of creditable seed for next boot
+erlinit: unmount_all
+erlinit: unmounting tmpfs at /sys/fs/cgroup...
+fixture: umount("/sys/fs/cgroup")
+erlinit: unmounting tmpfs at /dev/shm...
+fixture: umount("/dev/shm")
+erlinit: unmounting devpts at /dev/pts...
+fixture: umount("/dev/pts")
+erlinit: unmounting proc at /proc...
+fixture: umount("/proc")
+erlinit: unmounting sysfs at /sys...
+fixture: umount("/sys")
+EOF
diff --git a/tests/062_uniqueid_right b/tests/062_uniqueid_right
new file mode 100644
index 0000000..5840324
--- /dev/null
+++ b/tests/062_uniqueid_right
@@ -0,0 +1,96 @@
+#!/usr/bin/env bash
+
+#
+# Test that calling out to a unique id generator does the right thing
+#
+
+cat >"$CONFIG" <<EOF
+-v
+
+# Specify a hostname pattern that has a unique id part
+--hostname-pattern nerves-%-.4s-
+
+# Call out to a dummy unique id generator
+--uniqueid-exec "/usr/bin/make-unique-id"
+EOF
+
+cat >"$WORK/usr/bin/make-unique-id" <<EOF
+#!/usr/bin/env bash
+
+echo "12345678"
+EOF
+chmod +x "$WORK/usr/bin/make-unique-id"
+
+cat >"$EXPECTED" <<EOF
+erlinit: cmdline argc=1, merged argc=6
+erlinit: merged argv[0]=/sbin/init
+erlinit: merged argv[1]=-v
+erlinit: merged argv[2]=--hostname-pattern
+erlinit: merged argv[3]=nerves-%-.4s-
+erlinit: merged argv[4]=--uniqueid-exec
+erlinit: merged argv[5]=/usr/bin/make-unique-id
+fixture: mount("proc", "/proc", "proc", 14, data)
+fixture: mount("sysfs", "/sys", "sysfs", 14, data)
+fixture: mount("devtmpfs", "/dev", "devtmpfs", 42, data)
+fixture: mkdir("/dev/pts", 755)
+fixture: mkdir("/dev/shm", 1777)
+fixture: mount("devpts", "/dev/pts", "devpts", 10, data)
+fixture: symlink("/dev/mmcblk0","/dev/rootdisk0")
+fixture: symlink("/dev/mmcblk0p4","/dev/rootdisk0p4")
+fixture: symlink("/dev/mmcblk0p3","/dev/rootdisk0p3")
+fixture: symlink("/dev/mmcblk0p2","/dev/rootdisk0p2")
+fixture: symlink("/dev/mmcblk0p1","/dev/rootdisk0p1")
+erlinit: set_ctty
+fixture: setsid()
+fixture: mount("tmpfs", "/tmp", "tmpfs", 14, data)
+fixture: mount("tmpfs", "/run", "tmpfs", 14, data)
+erlinit: find_release
+erlinit: No release found in /srv/erlang.
+erlinit: find_erts_directory
+erlinit: setup_environment
+erlinit: setup_networking
+fixture: ioctl(SIOCGIFFLAGS)
+fixture: ioctl(SIOCSIFFLAGS)
+fixture: ioctl(SIOCGIFINDEX)
+erlinit: configure_hostname
+erlinit: system_cmd '/usr/bin/make-unique-id'
+erlinit: Hostname: nerves-5678-
+fixture: sethostname("nerves-5678-", 12)
+fixture: mkdir("/root/seedrng", 700)
+erlinit: Saving 256 bits of creditable seed for next boot
+erlinit: Env: 'HOME=/home/user0'
+erlinit: Env: 'PATH=/usr/sbin:/usr/bin:/sbin:/bin'
+erlinit: Env: 'TERM=xterm-256color'
+erlinit: Env: 'ROOTDIR=/usr/lib/erlang'
+erlinit: Env: 'BINDIR=/usr/lib/erlang/erts-6.0/bin'
+erlinit: Env: 'EMU=beam'
+erlinit: Env: 'PROGNAME=erlexec'
+erlinit: Arg: 'erlexec'
+erlinit: Arg: '-boot_var'
+erlinit: Arg: 'RELEASE_LIB'
+erlinit: Arg: '/srv/erlang/lib'
+erlinit: Launching erl...
+Hello from erlexec
+erlinit: Erlang VM exited
+erlinit: kill_all
+erlinit: Sending SIGTERM to all processes
+fixture: kill(-1, 15)
+fixture: sleep(1)
+erlinit: Sending SIGKILL to all processes
+fixture: kill(-1, 9)
+fixture: mkdir("/root/seedrng", 700)
+erlinit: Seeding 256 bits and crediting
+fixture: ioctl(RNDADDENTROPY)
+erlinit: Saving 256 bits of creditable seed for next boot
+erlinit: unmount_all
+erlinit: unmounting tmpfs at /sys/fs/cgroup...
+fixture: umount("/sys/fs/cgroup")
+erlinit: unmounting tmpfs at /dev/shm...
+fixture: umount("/dev/shm")
+erlinit: unmounting devpts at /dev/pts...
+fixture: umount("/dev/pts")
+erlinit: unmounting proc at /proc...
+fixture: umount("/proc")
+erlinit: unmounting sysfs at /sys...
+fixture: umount("/sys")
+EOF
diff --git a/tests/063_uniqueid_long_left b/tests/063_uniqueid_long_left
new file mode 100644
index 0000000..d9c8d70
--- /dev/null
+++ b/tests/063_uniqueid_long_left
@@ -0,0 +1,96 @@
+#!/usr/bin/env bash
+
+#
+# Test that calling out to a unique id generator does the right thing
+#
+
+cat >"$CONFIG" <<EOF
+-v
+
+# Specify a hostname pattern that has a unique id part
+--hostname-pattern nerves-%.10s-
+
+# Call out to a dummy unique id generator
+--uniqueid-exec "/usr/bin/make-unique-id"
+EOF
+
+cat >"$WORK/usr/bin/make-unique-id" <<EOF
+#!/usr/bin/env bash
+
+echo "123456789abcdef"
+EOF
+chmod +x "$WORK/usr/bin/make-unique-id"
+
+cat >"$EXPECTED" <<EOF
+erlinit: cmdline argc=1, merged argc=6
+erlinit: merged argv[0]=/sbin/init
+erlinit: merged argv[1]=-v
+erlinit: merged argv[2]=--hostname-pattern
+erlinit: merged argv[3]=nerves-%.10s-
+erlinit: merged argv[4]=--uniqueid-exec
+erlinit: merged argv[5]=/usr/bin/make-unique-id
+fixture: mount("proc", "/proc", "proc", 14, data)
+fixture: mount("sysfs", "/sys", "sysfs", 14, data)
+fixture: mount("devtmpfs", "/dev", "devtmpfs", 42, data)
+fixture: mkdir("/dev/pts", 755)
+fixture: mkdir("/dev/shm", 1777)
+fixture: mount("devpts", "/dev/pts", "devpts", 10, data)
+fixture: symlink("/dev/mmcblk0","/dev/rootdisk0")
+fixture: symlink("/dev/mmcblk0p4","/dev/rootdisk0p4")
+fixture: symlink("/dev/mmcblk0p3","/dev/rootdisk0p3")
+fixture: symlink("/dev/mmcblk0p2","/dev/rootdisk0p2")
+fixture: symlink("/dev/mmcblk0p1","/dev/rootdisk0p1")
+erlinit: set_ctty
+fixture: setsid()
+fixture: mount("tmpfs", "/tmp", "tmpfs", 14, data)
+fixture: mount("tmpfs", "/run", "tmpfs", 14, data)
+erlinit: find_release
+erlinit: No release found in /srv/erlang.
+erlinit: find_erts_directory
+erlinit: setup_environment
+erlinit: setup_networking
+fixture: ioctl(SIOCGIFFLAGS)
+fixture: ioctl(SIOCSIFFLAGS)
+fixture: ioctl(SIOCGIFINDEX)
+erlinit: configure_hostname
+erlinit: system_cmd '/usr/bin/make-unique-id'
+erlinit: Hostname: nerves-123456789a-
+fixture: sethostname("nerves-123456789a-", 18)
+fixture: mkdir("/root/seedrng", 700)
+erlinit: Saving 256 bits of creditable seed for next boot
+erlinit: Env: 'HOME=/home/user0'
+erlinit: Env: 'PATH=/usr/sbin:/usr/bin:/sbin:/bin'
+erlinit: Env: 'TERM=xterm-256color'
+erlinit: Env: 'ROOTDIR=/usr/lib/erlang'
+erlinit: Env: 'BINDIR=/usr/lib/erlang/erts-6.0/bin'
+erlinit: Env: 'EMU=beam'
+erlinit: Env: 'PROGNAME=erlexec'
+erlinit: Arg: 'erlexec'
+erlinit: Arg: '-boot_var'
+erlinit: Arg: 'RELEASE_LIB'
+erlinit: Arg: '/srv/erlang/lib'
+erlinit: Launching erl...
+Hello from erlexec
+erlinit: Erlang VM exited
+erlinit: kill_all
+erlinit: Sending SIGTERM to all processes
+fixture: kill(-1, 15)
+fixture: sleep(1)
+erlinit: Sending SIGKILL to all processes
+fixture: kill(-1, 9)
+fixture: mkdir("/root/seedrng", 700)
+erlinit: Seeding 256 bits and crediting
+fixture: ioctl(RNDADDENTROPY)
+erlinit: Saving 256 bits of creditable seed for next boot
+erlinit: unmount_all
+erlinit: unmounting tmpfs at /sys/fs/cgroup...
+fixture: umount("/sys/fs/cgroup")
+erlinit: unmounting tmpfs at /dev/shm...
+fixture: umount("/dev/shm")
+erlinit: unmounting devpts at /dev/pts...
+fixture: umount("/dev/pts")
+erlinit: unmounting proc at /proc...
+fixture: umount("/proc")
+erlinit: unmounting sysfs at /sys...
+fixture: umount("/sys")
+EOF
diff --git a/tests/064_uniqueid_long_right b/tests/064_uniqueid_long_right
new file mode 100644
index 0000000..1e3b6ef
--- /dev/null
+++ b/tests/064_uniqueid_long_right
@@ -0,0 +1,96 @@
+#!/usr/bin/env bash
+
+#
+# Test that calling out to a unique id generator does the right thing
+#
+
+cat >"$CONFIG" <<EOF
+-v
+
+# Specify a hostname pattern that has a unique id part
+--hostname-pattern nerves-%-.10s-
+
+# Call out to a dummy unique id generator
+--uniqueid-exec "/usr/bin/make-unique-id"
+EOF
+
+cat >"$WORK/usr/bin/make-unique-id" <<EOF
+#!/usr/bin/env bash
+
+echo "123456789abcdef"
+EOF
+chmod +x "$WORK/usr/bin/make-unique-id"
+
+cat >"$EXPECTED" <<EOF
+erlinit: cmdline argc=1, merged argc=6
+erlinit: merged argv[0]=/sbin/init
+erlinit: merged argv[1]=-v
+erlinit: merged argv[2]=--hostname-pattern
+erlinit: merged argv[3]=nerves-%-.10s-
+erlinit: merged argv[4]=--uniqueid-exec
+erlinit: merged argv[5]=/usr/bin/make-unique-id
+fixture: mount("proc", "/proc", "proc", 14, data)
+fixture: mount("sysfs", "/sys", "sysfs", 14, data)
+fixture: mount("devtmpfs", "/dev", "devtmpfs", 42, data)
+fixture: mkdir("/dev/pts", 755)
+fixture: mkdir("/dev/shm", 1777)
+fixture: mount("devpts", "/dev/pts", "devpts", 10, data)
+fixture: symlink("/dev/mmcblk0","/dev/rootdisk0")
+fixture: symlink("/dev/mmcblk0p4","/dev/rootdisk0p4")
+fixture: symlink("/dev/mmcblk0p3","/dev/rootdisk0p3")
+fixture: symlink("/dev/mmcblk0p2","/dev/rootdisk0p2")
+fixture: symlink("/dev/mmcblk0p1","/dev/rootdisk0p1")
+erlinit: set_ctty
+fixture: setsid()
+fixture: mount("tmpfs", "/tmp", "tmpfs", 14, data)
+fixture: mount("tmpfs", "/run", "tmpfs", 14, data)
+erlinit: find_release
+erlinit: No release found in /srv/erlang.
+erlinit: find_erts_directory
+erlinit: setup_environment
+erlinit: setup_networking
+fixture: ioctl(SIOCGIFFLAGS)
+fixture: ioctl(SIOCSIFFLAGS)
+fixture: ioctl(SIOCGIFINDEX)
+erlinit: configure_hostname
+erlinit: system_cmd '/usr/bin/make-unique-id'
+erlinit: Hostname: nerves-6789abcdef-
+fixture: sethostname("nerves-6789abcdef-", 18)
+fixture: mkdir("/root/seedrng", 700)
+erlinit: Saving 256 bits of creditable seed for next boot
+erlinit: Env: 'HOME=/home/user0'
+erlinit: Env: 'PATH=/usr/sbin:/usr/bin:/sbin:/bin'
+erlinit: Env: 'TERM=xterm-256color'
+erlinit: Env: 'ROOTDIR=/usr/lib/erlang'
+erlinit: Env: 'BINDIR=/usr/lib/erlang/erts-6.0/bin'
+erlinit: Env: 'EMU=beam'
+erlinit: Env: 'PROGNAME=erlexec'
+erlinit: Arg: 'erlexec'
+erlinit: Arg: '-boot_var'
+erlinit: Arg: 'RELEASE_LIB'
+erlinit: Arg: '/srv/erlang/lib'
+erlinit: Launching erl...
+Hello from erlexec
+erlinit: Erlang VM exited
+erlinit: kill_all
+erlinit: Sending SIGTERM to all processes
+fixture: kill(-1, 15)
+fixture: sleep(1)
+erlinit: Sending SIGKILL to all processes
+fixture: kill(-1, 9)
+fixture: mkdir("/root/seedrng", 700)
+erlinit: Seeding 256 bits and crediting
+fixture: ioctl(RNDADDENTROPY)
+erlinit: Saving 256 bits of creditable seed for next boot
+erlinit: unmount_all
+erlinit: unmounting tmpfs at /sys/fs/cgroup...
+fixture: umount("/sys/fs/cgroup")
+erlinit: unmounting tmpfs at /dev/shm...
+fixture: umount("/dev/shm")
+erlinit: unmounting devpts at /dev/pts...
+fixture: umount("/dev/pts")
+erlinit: unmounting proc at /proc...
+fixture: umount("/proc")
+erlinit: unmounting sysfs at /sys...
+fixture: umount("/sys")
+EOF
diff --git a/tests/065_uniqueid_bad b/tests/065_uniqueid_bad
new file mode 100644
index 0000000..d3869df
--- /dev/null
+++ b/tests/065_uniqueid_bad
@@ -0,0 +1,96 @@
+#!/usr/bin/env bash
+
+#
+# Test that calling out to a unique id generator does the right thing
+#
+
+cat >"$CONFIG" <<EOF
+-v
+
+# Specify a hostname pattern that has a unique id part
+--hostname-pattern nerves-%d-
+
+# Call out to a dummy unique id generator
+--uniqueid-exec "/usr/bin/make-unique-id"
+EOF
+
+cat >"$WORK/usr/bin/make-unique-id" <<EOF
+#!/usr/bin/env bash
+
+echo "12345678"
+EOF
+chmod +x "$WORK/usr/bin/make-unique-id"
+
+cat >"$EXPECTED" <<EOF
+erlinit: cmdline argc=1, merged argc=6
+erlinit: merged argv[0]=/sbin/init
+erlinit: merged argv[1]=-v
+erlinit: merged argv[2]=--hostname-pattern
+erlinit: merged argv[3]=nerves-%d-
+erlinit: merged argv[4]=--uniqueid-exec
+erlinit: merged argv[5]=/usr/bin/make-unique-id
+fixture: mount("proc", "/proc", "proc", 14, data)
+fixture: mount("sysfs", "/sys", "sysfs", 14, data)
+fixture: mount("devtmpfs", "/dev", "devtmpfs", 42, data)
+fixture: mkdir("/dev/pts", 755)
+fixture: mkdir("/dev/shm", 1777)
+fixture: mount("devpts", "/dev/pts", "devpts", 10, data)
+fixture: symlink("/dev/mmcblk0","/dev/rootdisk0")
+fixture: symlink("/dev/mmcblk0p4","/dev/rootdisk0p4")
+fixture: symlink("/dev/mmcblk0p3","/dev/rootdisk0p3")
+fixture: symlink("/dev/mmcblk0p2","/dev/rootdisk0p2")
+fixture: symlink("/dev/mmcblk0p1","/dev/rootdisk0p1")
+erlinit: set_ctty
+fixture: setsid()
+fixture: mount("tmpfs", "/tmp", "tmpfs", 14, data)
+fixture: mount("tmpfs", "/run", "tmpfs", 14, data)
+erlinit: find_release
+erlinit: No release found in /srv/erlang.
+erlinit: find_erts_directory
+erlinit: setup_environment
+erlinit: setup_networking
+fixture: ioctl(SIOCGIFFLAGS)
+fixture: ioctl(SIOCSIFFLAGS)
+fixture: ioctl(SIOCGIFINDEX)
+erlinit: configure_hostname
+erlinit: system_cmd '/usr/bin/make-unique-id'
+erlinit: Hostname: nerves-
+fixture: sethostname("nerves-", 7)
+fixture: mkdir("/root/seedrng", 700)
+erlinit: Saving 256 bits of creditable seed for next boot
+erlinit: Env: 'HOME=/home/user0'
+erlinit: Env: 'PATH=/usr/sbin:/usr/bin:/sbin:/bin'
+erlinit: Env: 'TERM=xterm-256color'
+erlinit: Env: 'ROOTDIR=/usr/lib/erlang'
+erlinit: Env: 'BINDIR=/usr/lib/erlang/erts-6.0/bin'
+erlinit: Env: 'EMU=beam'
+erlinit: Env: 'PROGNAME=erlexec'
+erlinit: Arg: 'erlexec'
+erlinit: Arg: '-boot_var'
+erlinit: Arg: 'RELEASE_LIB'
+erlinit: Arg: '/srv/erlang/lib'
+erlinit: Launching erl...
+Hello from erlexec
+erlinit: Erlang VM exited
+erlinit: kill_all
+erlinit: Sending SIGTERM to all processes
+fixture: kill(-1, 15)
+fixture: sleep(1)
+erlinit: Sending SIGKILL to all processes
+fixture: kill(-1, 9)
+fixture: mkdir("/root/seedrng", 700)
+erlinit: Seeding 256 bits and crediting
+fixture: ioctl(RNDADDENTROPY)
+erlinit: Saving 256 bits of creditable seed for next boot
+erlinit: unmount_all
+erlinit: unmounting tmpfs at /sys/fs/cgroup...
+fixture: umount("/sys/fs/cgroup")
+erlinit: unmounting tmpfs at /dev/shm...
+fixture: umount("/dev/shm")
+erlinit: unmounting devpts at /dev/pts...
+fixture: umount("/dev/pts")
+erlinit: unmounting proc at /proc...
+fixture: umount("/proc")
+erlinit: unmounting sysfs at /sys...
+fixture: umount("/sys")
+EOF