# cat /proc/sys/kernel/pid_max
32768
# sysctl -a|grep pid_max
kernel.pid_max = 32768

# sysctl -h
Usage:
 sysctl [options] [variable[=value] ...]
Options:
 -a, --all   display all variables
 -A     alias of -a
 -X     alias of -a
  --deprecated  include deprecated parameters to listing
 -b, --binary   print value without new line
 -e, --ignore   ignore unknown variables errors
 -N, --names   print variable names without values
 -n, --values   print only values of a variables
 -p, --load[=] read values from file
 -f     alias of -p
  --system   read values from all system directories
 -r, --pattern 
      select setting that match expression
 -q, --quiet   do not echo variable set
 -w, --write   enable writing a value to variable
 -o     does nothing
 -x     does nothing
 -d     alias of -h
 -h, --help  display this help and exit
 -V, --version output version information and exit
For more details see sysctl(8).