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sma_cp — Lock-safe file copy

Theme: Configure
Who Is It For? System Administrator

What is it?​

sma_cp copies a file to a lock-managed destination, acquiring a write lock on the target before copying to prevent conflicts when another process is simultaneously reading the file.

Use sma_cp in place of the standard cp command when updating files that the agent reads at runtime — specifically the FAD control file and the SMA_RM configuration file — to avoid crashes caused by a read/write race condition.

  • Use sma_cp when updating a FAD control file that is actively monitored by a running sma_fad process.
  • Use sma_cp when updating SMA_RM.conf while the sma_RM process is running.
  • Use the standard cp command for all other file copy operations. sma_cp is only needed for lock-managed agent configuration files.

Syntax​

sma_cp <from_file> <to_file>
ArgumentDescription
<from_file>Full path to the source file to copy from
<to_file>Full path of the destination file to copy to. The destination must be a lock-managed file.

Behavior​

  1. sma_cp acquires an exclusive write lock on the destination file.
  2. If the lock is not available within 5 seconds, sma_cp exits with an error.
  3. Once the lock is held, the source file is copied to the destination byte-by-byte.
  4. The destination file is truncated to the source file size after copying.
  5. The lock is released when the destination file is closed.
Example

The following command replaces an active FAD control file with an updated version:

sma_cp /tmp/control_new.xml $LSAM_ROOT/fad/$SMA_LSAM_INSTANCE/control/control.xml

Exit codes​

CodeCondition
0Success — file copied successfully
-1Error — destination stat failed, file open failed, lock acquisition timed out, truncate failed, or copy failed

Exception handling​

sma_cp returns -1 with no file copied — The write lock on the destination could not be acquired within 5 seconds. Another process is holding the lock. — Wait for the lock-holding process to release the file, then retry. If the condition persists, check that sma_fad or sma_RM is running normally.