I found this in one of the bash scripts for capturing metrics running on CentOS.
read -rd '' count <<< "$count"
I know read reads the content of file descriptor into buffer, but I cannot find the documentation for the command line switches -r, -d.
Additionally, What does triple left arrow <<< do?
All of these are Bash features which you will find amply documented in the Bash manual.
<<< is "here string" format; it's sort of like a here document:
cat <<____HERE
Hello, World!
____HERE
... except the token after the separator is the actual string to pass in as standard input to the command.
The -r option to read disables some legacy behavior with backslashes from the original Bourne shell.
-d sets the record delimiter. An empty string says to stop reading when you get a NUL character.