Bash/Mgrep

This is a useful tool that extends grep.

• Expression input is at the front, allowing quick & easy editing
• Search directory defaults to ., but can be easily modified
• Files checked defaults to '*.c', '*.cpp' and '*.h', but can be easily changed
• Recursively locates all files matching given names (e.g: *.c)
• Multiple filenames / masks / patterns may be specified
• Uses grep's extended regex mode
• Output shows file and line number, and is highlighted
• If the output flows over the screen, less allows you to review the results
• If the output doesnt flow over the screen, less quits immediately
• Automatically detects if the output is to a terminal or pipe, utilizing less and highlighting for the former
• By default uses case insensitive search, just setting GREP_OPTIONS (even to empty) will disable this

#!/bin/bash
 
if [ $# -lt 1 ]; then
  echo "usage:"
  echo "  $0 <expression> [directory] [filename..]"
  exit 1
fi
 
EXPRESSION="$1";    shift
 
if [ $# -lt 1 ]; then
  DIRECTORY="."
else
  DIRECTORY="$1";     shift
fi
 
if [ $# -lt 1 ]; then
  FILES="-name '*.c' -or -name '*.cpp' -or -name '*.h'"
else
  FILES="-name '$1'"; shift
  while [ $# -ne 0 ]; do
    FILES="${FILES} -or -name '$1'"; shift
  done
fi
CMD="find \"${DIRECTORY}\" ${FILES}"
 
if [ -t 1 ]; then
  PIPE=/tmp/$$.mgrep
  #trap "exec 1>&-; sleep 0.1; rm -f ${PIPE}" EXIT
  mknod ${PIPE} p
  less -FKnRX < ${PIPE} &
  exec 3>&1
  exec 1>${PIPE}
  GREP_OPTIONS="--color=always ${GREP_OPTIONS}"
else
  PIPE=""
fi
 
eval ${CMD} | \
while read -r f; do
  grep -niH -E ${GREP_OPTIONS} -- "${EXPRESSION}" "${f}"
done
 
if [ "${PIPE}" != "" ]; then
  exec 1>&3
  exec 3>&-
  wait
  rm -f ${PIPE}
fi