File not recognized when passed as argument

Shell Programming and Scripting
1

I have the below script in file read_file.ksh

if [[ $# -ne 1 ]] || [[ $# -gt 1 ]]
then

echo "Required one input file"
echo "Enter a file to get char count:"
read $FILE_NAME
if [[ -f $FILE_NAME ]]
        then
         echo "valid file"
        else
        echo "Not a valid file."
fi

When run as read_file.ksh detail.csv or read_file.ksh ~/ded/incoming/detail.csv it works fine. But when i run the script alone w/out the argument as

as given in the script it prompts as

and when i enter the file along with the full path, its not recognized as a file.

Pls throw some light.

2
  • I think it makes no sense to check if there is not exactly 1 parameter or more than 1. More than 1 is also not equal 1.
  • When using read into a variable, leave out the leading $.

Your script could look like:

if [[ $# -ne 1 ]]; then
        echo "Required one input file"
        exit 1
fi

echo "Enter a file to get char count:"
read FILE_NAME

if [[ -f $FILE_NAME ]]; then
        echo "valid file"
else
        echo "Not a valid file."
fi

exit 0
3

Remove "$" while readign input

read FILE_NAME
4

Your concern is correct. The requirement here is the user need to enter only one file as argument. If he enters more than one file or none it prompts for a input file.
Actually if he enters one file as read_file.ksh detail.csv it works fine - as i have kept this check in diff part of the script which i have not included in the original post. Below is the full script.

if [[ $# -ne 1 ]] || [[ $# -gt 1 ]]
then

echo "Required one input file"
echo "Enter a file to get char count:"
read FILE_NAME
if [[ -f $FILE_NAME ]]
        then
         echo "valid file"
        else
        echo "Not a valid file."
else
        FILE_NAME=$1
        if [[ -f $1 ]]
        then
        echo "valid file to get char count"
        else
        echo "Not a valid file to get char count."
fi

@pravin27: sorry that $FILE_NAME is a typo.

5

Idea using case. Having just read your last post, my version will through a "usage" error if there is more than one parameter.

script_name=`basename $0`
param_count=$#
case ${param_count}
in
        0)      echo "Enter a file to get char count:"
                read FILE_NAME
                ;;
        1)      FILE_NAME="$1"
                continue
                ;;
        *)      echo "Usage: ${script_name} filename"
                exit 1
                ;;
esac

if [ -f "${FILE_NAME}" ]
then
        echo "valid file : ${FILE_NAME}"
else
        echo "Not a valid file : ${FILE_NAME}"
fi
6

Thanks! But im getting the same error. i.e when the param_count=0 the script prompts for the input file and when it's given as full path

it does not recognize the *.csv file and echo's "Not a valid file ..."
No issues when given as detail.csv (without the full path.)

---------- Post updated at 07:50 PM ---------- Previous update was at 06:46 PM ----------

Guess the shell does not expand the variable when given in full path

7

Interesting you are correct. When the filename is entered into the read statement rather than on the command line it does indeed not expand the ~username.

Fix highlighted in script below.

script_name=`basename $0`
param_count=$#
case ${param_count}
in
        0)
                echo "Enter a file to get char count:"
                read FILE_NAME
                ;;
        1)      FILE_NAME="$1"
                continue
                ;;
        *)      echo "Usage: ${script_name} filename"
                exit 1
                ;;
esac

FILE_NAME=`eval echo "${FILE_NAME}"`

if [ -f "${FILE_NAME}" ]
then
        echo "valid file : ${FILE_NAME}"
else
        echo "Not a valid file : ${FILE_NAME}"
fi
8

Lovely..Thanks.
So do we need to use eval to expand variables?

---------- Post updated at 12:29 PM ---------- Previous update was at 11:01 AM ----------

Moreover why have you used continue command in the case statement. Im gettint cannot continue error.I use ksh.

9

Oops. Delete "continue" line - it's a paste error.

The eval is only to cause shell to look at special shell variables (like ~) after the shell program has been interpreted. I've also seen it used where a script generates an environment variable name on the fly.

10

ok. Guess the continue for case statement doesn't work in ksh. When i ran the script in /bin/sh it returned no error for the continue statement.
Thanks much!