replacestring

#!/bin/bash
#
# regexp replace a string by another in a files (inplace!)
# needs perl
# version 2.1
# author: joerg arndt (arndt@jjj.de)
#

set -

########################################

function usage
{
THIS=`basename $0`;
cat <<EOF
  Usage:
  $THIS [OPTION] OLDEXPR  NEWEXPR  FILE1  [ FILE2 FILE3 ... ]
  OLDEXPR and NEWEXPR should usually be in single quotes.
  Use perl regexp syntax.
  (e.g. unescaped chars "()^$" have special meanings).
  OPTION must be first argument
  OPTION "-i" sets interactive mode, i.e.
  you will be asked for confirmation before each file is changed.
  (interactive mode is the default).
  OPTION "-f" sets non interactive mode (beware!).
  EXAMPLES:
  $THIS old_func_name new_func_name *.cc
  $THIS 'old_func_name_([a-z]+)' 'new_func_name_$1' *.cc
  find . -name *.cc -exec $THIS old_func_name new_func_name {} \;
EOF
exit -1 ;
}

if [ $# -lt 3 ]; then  usage;  fi
if [ "$1" = "-h" ]; then  usage;  fi
if [ "$1" = "-?" ]; then  usage;  fi
if [ "$1" = "--help" ]; then  usage;  fi
if [ "$1" = "-help" ]; then  usage;  fi


########################################

INTERACTIVE=1;

if [ "$1" = "-f" ]; then  INTERACTIVE=0; shift;  fi

if [ "$1" = "-i" ]; then  INTERACTIVE=1; shift;  fi


OLDEXPR=$1
NEWEXPR=$2
shift
shift


if [ -z "$OLDEXPR" ]; then
    echo 'empty OLDEXPR !';
    echo ' (exiting) ';
    exit -1;
fi


TMP=/tmp/replace.$$.tmp
BAK=/tmp/replace.$$.bak


########################################
for FILE in  $*; do
    echo " FILE $FILE : ";

    ## skip zero byte files:
    if [ ! -s $FILE ]; then
        echo "skipping $FILE (has length zero)";
	continue;
    fi

    ## skip symbolic links:
    if [ -L $FILE ]; then
        echo "skipping $FILE (symbolic link)";
	continue;
    fi

    ## skip directories:
    if [ -d $FILE ]; then
        echo "skipping $FILE (directory)";
	continue;
    fi

    ## must be readable:
    if [ ! -r $FILE ]; then
        echo "skipping $FILE (not readable)";
	continue;
    fi

    ## must be writable:
    if [ ! -w $FILE ]; then
        echo "skipping $FILE (not writeable)";
	continue;
    fi

    ## file exists and a regular file ?:
    if [ ! -f $FILE ]; then
        echo "skipping $FILE (it does not exist or is no regular file)";
	continue;
    fi

    cp $FILE $BAK  ## create backup

    cp $FILE $TMP;  ## to have identical permissions for new file

    ############################
    ## work is done here:

    LINE1="\$cmd='s/$OLDEXPR/$NEWEXPR/g'; ";
    LINED="print \"cmd=[[\",\$cmd,\"]]\n\"; ";  ## debug
    LINE2="while(<STDIN>) {eval(\$cmd); print;}"
    perl -we "$LINE1 $LINE2" < $FILE  > $TMP;
#    perl -we "$LINE1 $LINED $LINE2" < $FILE  > $TMP;

    ############################

    ## created zero byte file ?
    ## most likely an error in the regexpressions
    if [ ! -s $TMP ]; then
        echo 'zero filesize !  (exiting)';
        exit -1;
    fi

    if [ "$INTERACTIVE" = "0" ]; then
        ## non-interactive: replace if file changed
        if ! diff $FILE $TMP; then
            mv $TMP $FILE;
        fi
    else
        ## interactive: replace if file changed & user says ok
        if ! diff $FILE $TMP; then
            echo -n "accept these changes ('y' for ok) ?";
            read answer;
            if [ "$answer" = "y" ]; then
                echo "changes accepted."
                mv $TMP $FILE;
            else
                echo "changes rejected."
            fi
        fi
    fi
done


rm -f $TMP
rm -f $BAK

exit 0;

########################################