nlmconv

nlmconv <filename>

nlmconv is a utility from the nfs-utils package. Its primary function is to convert binary Network Lock Manager (NLM) monitor files into a human-readable text format. These monitor files, typically found in directories like /var/lib/nfs/statd/sm, store information about remote hosts that the rpc.statd (status monitor) daemon is monitoring for NLM-related purposes.
By converting these files, system administrators can inspect the current state of NLM-monitored clients and servers, which is crucial for diagnosing network file locking issues in NFS environments. The command reads the specified binary file and prints its converted textual content to standard output. nlmconv serves as an essential tool for debugging and maintaining NFS client/server stability when dealing with advisory file locking.

Caveats and Limitations:
Requires the nfs-utils package to be installed.
The command expects a specific binary format; using it on arbitrary files will likely result in unreadable output or errors.
Its utility is specific to environments utilizing NFS with NLM for file locking.
Output is always to standard output; there is no option for an output file.

NLM monitor files are typically located under /var/lib/nfs/statd/sm/ on Linux systems. Each file within this directory usually corresponds to a monitored host.

The Network Lock Manager (NLM) protocol is an integral part of the Network File System (NFS), designed to provide advisory file locking capabilities across a network. nlmconv was developed as part of the nfs-utils suite, which provides essential tools for managing NFS services.
Its existence reflects the need for system administrators to have visibility into the state of NLM's monitoring service (rpc.statd), particularly for debugging and ensuring proper file locking behavior in complex distributed environments. Its purpose remains consistent since its introduction: to translate internal, machine-readable NLM state files into an understandable format.

rpc.statd(8), rpc.lockd(8), nfsd(8), mountd(8), nfs(5), exports(5)