So, I decided to run a test. It turns out we are both wrong. My test script is as follows: #====================================================================== #!/bin/bash # Remote machine MACH=dianne.skoll.ca # Create a 10MB pseudo-random file echo "`date` Creating 10MB file" FILE=pseudo-random dd if=/dev/urandom bs=1k count=10k of=$FILE 2>/dev/null # Rsync it over at 500kB per second in the background echo "`date` Starting rsync" rsync -c --verbose --bwlimit=500k $FILE $MACH:/tmp & RSYNC_PID=$! echo "`date` rsync PID=$RSYNC_PID; sleeping for 3 seconds" # Sleep for 3 seconds sleep 3 echo "`date` Stopping rsync" # Stop the rsync kill -STOP $RSYNC_PID echo "`date` Changing source file" # Change the source file dd if=/dev/urandom bs=1k count=10k of=$FILE 2>/dev/null echo "`date` Continuing rsync" # Restart the rsync and bring it into the foreground kill -CONT $RSYNC_PID wait echo "`date` Rsync done; comparing files" ssh $MACH "cd /tmp && sha1sum $FILE" | sha1sum -c - #====================================================================== Running it produces this output: Wed Feb 28 14:14:32 EST 2018 Creating 10MB file Wed Feb 28 14:14:32 EST 2018 Starting rsync Wed Feb 28 14:14:32 EST 2018 rsync PID=24456; sleeping for 3 seconds pseudo-random Wed Feb 28 14:14:35 EST 2018 Stopping rsync Wed Feb 28 14:14:35 EST 2018 Changing source file Wed Feb 28 14:14:35 EST 2018 Continuing rsync sent 10,488,419 bytes received 19,505 bytes 488,740.65 bytes/sec total size is 10,485,760 speedup is 1.00 Wed Feb 28 14:14:53 EST 2018 Rsync done; comparing files pseudo-random: FAILED sha1sum: WARNING: 1 computed checksum did NOT match So even *with* the -c flag, rsync didn't notice the file had been changed while it was running. Interesting. Regards, Dianne.
