Search and Replace Function (homework)

[hunter108]

I'm trying to write what is basically a search and replace script. Full disclosure: This IS a homework assignment, and my attempt is below. It is supposed to have a usage statement, which I think is pretty solid so far. The problem is at the end where I do that actual searching and replacing. I'm just getting the 'end of file unexpected' error, which because i am spoiled in my young programming life with gcc, g++, and java compilers that neatly tell you where the problem is, I don't really know what is going wrong.

I think that error means it is looking for something it can't find, right? What?

Thanks in advance if anyone helps.

#!/bin/sh

# a shell function to print and error message and exit the script
error_and_die ()
    {
    echo "$@" >&2
    exit 1

    }
# a shell function to print and error message and a usage message and
# to exit the script
error_and_die_with_usage ()
    {
    echo "$@" >&2
    usage
    exit 1
    }

# a shell function to print a usage message
usage ()
{
echo "
change-lines [-n] -s search string -r replace string files ...

    -n    do not backup the original file
    -s    search string the search for this string
    -r    replace string replace the search string with this string
    -h    print this message
"  >&2
}


backup_file=TRUE
search_string=
replace_string=

while :
    do
    case $1 in
    -n)
       backup_file=FALSE
       ;;
    -s)
        if [ ! "$2" ]
            then
            error_and_die_with_usage "Search String not specified with -s"
            fi
        search_string="$2"
        shift 
        ;;
    -r)
        if [ ! "$2" ]
            then
            error_and_die_with_usage "Search String not specified with -r"
            fi
        replace_string="$2"
        shift 
        ;;
    -h)
        usage
        exit 0
        ;;
    -?)
        error_and_die_with_usage "This should help!"
        ;;
    *)
        break
        ;;
    esac
    shift
    done

if [ ! "$search_string" -a ! "$replace_string"  -a $# -eq 0 ]
    then
    error_and_die_with_usage "No Search String, Replace String, or file to edit entered."
    fi

if [ ! "$search_string" -a ! "$replace_string" ]
    then
    error_and_die_with_usage "No Search or Replace String entered.
    fi

if [ ! "$search_string" -a $# -eq 0 ]
    then
    error_and_die_with_usage "No Search String or file to edit entered."
    fi

if [ ! "$search_string" ]
    then
    error_and_die_with_usage "No Search String entered."
    fi

if [ ! "$replace_string"  -a $# -eq 0 ]
    then
    error_and_die_with_usage "No Replacement String or file to edit entered."
    fi

if [ ! "$replace_string" ]
    then
    error_and_die_with_usage "No Replacement String entered."
    fi

if [ $# -eq 0 ]
    then
    error_and_die_with_usage "No file to edit entered."
    fi

# here is where I am pretty sure I am getting an error.
for file in $*
    do
                backup=$1
                if ( backup_file == TRUE )
                then
                      cp $backup $backup.keep
                fi
                sed 's/$search_string/$replace_string/g' $backup
                shift
    done

        exit 0;

[drl]

Hi.

One shell debugging tool is

set -x

place such a line after the shebang line, and see if that helps.

If you need to post more code, please use CODE tags: select the text with the mouse and then click the # above the editing window ... cheers, drl

[hunter108]

That is exactly what I needed. I know it's a simple tip, but thank you very much for it. I haven't fixed it yet, but at least I'm not in a black hole staring it down.

[lomcevak]

To get the most debugging information you can use:

set -vx

If you don't want to put that in your script you can specify it when you run the script:

sh -vx ./script

[kurtdriver]

You can set the -x in the first line too.

#!/bin/bash -vx

On a related note, what do the plus signs indicate?

 echo "Do you want to input a fraction of an hour or a whole number?"
+ echo 'Do you want to input a fraction of an hour or a whole number?'
Do you want to input a fraction of an hour or a whole number?
  echo "f or w?"
+ echo 'f or w?'
f or w?
   read RESPONSE
+ read RESPONSE

This part works, but I don't understand how to interpret it. The plus signs don't appear in the if loop, though.