ifstats

#! /bin/sh

# ifstats - print interface statistics (counters) on Linux
#
# Copyright (C) 2017,2024 by Erik Auerswald <auerswal@unix-ag.uni-kl.de>
#
# Copying and distribution of this file, with or without modification,
# are permitted in any medium without royalty provided the copyright
# notice and this notice are preserved.  This file is offered as-is,
# without any warranty.

set -u

PROG="$(basename "$0")"
VERSION='2024-09-22-01'

print_version()
{
  printf -- '%s version %s\n' "${PROG}" "${VERSION}"
}

print_copyright()
{
  echo 'Copyright (C) 2017,2024 by Erik Auerswald <auerswal@unix-ag.uni-kl.de>'
}

print_license()
{
  cat <<EOL
Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.  This file is offered as-is,
without any warranty.

EOL
}

print_usage()
{
  cat <<EOU
Usage: ${PROG} { -h | -V | -L }
       ${PROG} [-n] [INTERFACE...]
EOU
}

print_help()
{
  print_version
  print_copyright
  print_license
  echo 'print interface statistics (counters) on Linux'
  print_usage
  cat <<EOH
Options:
  -h      print this help and exit
  -V      print version information and exit
  -L      print license and exit
  -n      omit zero count statistics
Examples:
  ${PROG}
  ${PROG} eth0
  ${PROG} eth1 eth2
EOH
}

SYS_CLASS_NET='/sys/class/net'
EXITCODE=0
ALLPATTERN='.'
ZEROPATTERN='^0'
GREPOPTS='-H'
GREPPAT=${ALLPATTERN}

while getopts ':hVLn' OPT; do
  case "${OPT}" in
    'h') print_help; exit 0;;
    'V') print_version; print_copyright; exit 0;;
    'L') print_version; print_copyright; echo; print_license; exit 0;;
    'n') GREPOPTS="${GREPOPTS} -v"; GREPPAT=${ZEROPATTERN};;
    '?') echo "${PROG}: error: unknown option '-$OPTARG'";
         print_usage; exit 1;;
    ':') echo "${PROG}: error: argument required for option '-$OPTARG'";
         print_usage; exit 1;;
    *) echo "${PROG}: error: getopts() failure"; exit 1;;
  esac
done
shift $((OPTIND - 1))

cd "${SYS_CLASS_NET}"

test $# -eq 0 && ifnames=$(ls -1) || ifnames="$*"

for i in ${ifnames}; do
  test -d "${i}/statistics" ||
    { echo "% error: no interface ${i}"; EXITCODE=1 continue; }
  echo "interface ${i}:"
  cd "${i}/statistics"
  grep ${GREPOPTS} -- "${GREPPAT}" * | sed 's/^/  /;s/:\([0-9]\)/: \1/'
  cd "${SYS_CLASS_NET}"
done

exit "${EXITCODE}"