Bash/Mgrep

This is a useful tool that extends grep.

• Expression input is at the front, allowing quick & easy editing
• Recursively locates all files named (e.g: *.c)
• Files checked defaults to '*.c' and '*.h', but can be easily changed
• Multiple filenames / masks 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

#!/bin/bash
 
if [ $# -lt 2 ]; then
  echo "usage:"
  echo "  $0 <expression> <directory> [filename..]"
  exit 1
fi
 
EXPRESSION="$1";    shift
DIRECTORY="$1";     shift
 
if [ $# -lt 1 ]; then
  FILES="-name '*.c' -or -name '*.h'"
else
  FILES="-name '$1'"; shift
  while [ $# -ne 0 ]; do
    FILES="${FILES} -or -name '$1'"; shift
  done
fi
 
if [ -t 1 ]; then
  PIPE=/tmp/$$.mgrep
  trap "rm -f ${PIPE}" EXIT
  mknod ${PIPE} p
  less -FKnRX < ${PIPE} &
  exec 1>&-
  exec 1>${PIPE}
  GREP_OPTIONS="--color=always ${GREP_OPTIONS}"
fi
 
CMD="find \"${DIRECTORY}\" ${FILES}"
eval ${CMD} | \
while read -r f; do
  grep -niH -E ${GREP_OPTIONS} "${EXPRESSION}" "${f}"
done