$ gdisk /tmp/emmc.img 
GPT fdisk (gdisk) version 1.0.10
  
Partition table scan:
  MBR: not present
  BSD: not present
  APM: not present
  GPT: not present
  
Creating new GPT entries in memory.
 
Command (? for help): n
Partition number (1-128, default 1): 
First sector (34-32734, default = 2048) or {+-}size{KMGTP}: 
Last sector (2048-32734, default = 30719) or {+-}size{KMGTP}: 
Current type is 8300 (Linux filesystem)
Hex code or GUID (L to show codes, Enter = 8300): 
Changed type of partition to 'Linux filesystem'

Command (? for help): i
Using 1
Partition GUID code: 0FC63DAF-8483-4772-8E79-3D69D8477DE4 (Linux filesystem)
Partition unique GUID: 8B5424CF-C8D3-4B21-BE37-66D7FC61B1BC
First sector: 2048 (at 1024.0 KiB)
Last sector: 30719 (at 15.0 MiB)
Partition size: 28672 sectors (14.0 MiB)
Attribute flags: 0000000000000000
Partition name: 'Linux filesystem'

Command (? for help): w
  
Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING
PARTITIONS!!
  
Do you want to proceed? (Y/N): y
OK; writing new GUID partition table (GPT) to emmc.img.
Warning: The kernel is still using the old partition table.
The new table will be used at the next reboot or after you
run partprobe(8) or kpartx(8)
The operation has completed successfully.
$