getdtablesize - Linux


getdtablesize retrieves the maximum number of file descriptors that a process can open simultaneously. It is commonly used to determine system resource limits and monitor system performance.


getdtablesize [-a]


| Flag | Description | Default |
| -a | Display system-wide limit, not per-process limit | false |


Example 1: Get per-process file descriptor limit:


Example 2: Get system-wide file descriptor limit:

getdtablesize -a

Common Issues

  • Negative value: If the command returns a negative value, it indicates an error occurred. Check the system logs for details.
  • Unexpected value: If the returned value seems unreasonably low, it may indicate a resource exhaustion situation. Investigate system resource usage to identify the cause.


  • Use with ulimit to modify or view user-specific file descriptor limits.
  • Combine with sysctl to configure system-wide file descriptor limits.

Related Commands

  • ulimit
  • sysctl