Hi all,

I am trying to delete columns in a file using a script. The columns that need to be deleted are passed as arguments to the script.

The script should look like this

Code:

> delete_columns.sh <file_name.txt> <column_numbers_to_be_deleted>

The contents of the file_name.txt will be like

Code:

abcd
cdef
opqr

On running the script with the following arguments

Code:

> delete_columns.sh file_name.txt 4 2

the output should look like

Code:

ac
ce
oq

I wrote the following script which works with as mentioned

Code:

# This for loop removes the first argument i.e., file_name and keeps the remaining arguments in the shell variable columns_num_list
# So in the above example if arguments passed are file_name.txt 4 2
# the variable content after for loop will be columns_num_list="2,4"

for (( i = 2; i <= $#; i++ ))
do

	if [ $i -eq 2 ] 
	then 
		columns_num_list="${!i}"
	else
		columns_num_list="${!i},"$columns_num_list
	fi
done

# This command deletes the columns mentioned by columns_num_list variable
# This translates to cut --complement -c2,4 file_name.txt > file_with_columns_removed.txt

cut --complement -c$columns_num_list  $1 > file_with_columns_removed.txt

The issue is that the person who is using this script doesn't have

Code:

 --complement

option to cut command. So this script is not useful.

I have tried to explore other options like awk and couldn't actually get much headway.

Please help me in resolving this issue.
Also I am at a very beginner level in bash scripting and trying to learn. So any suggestions to improve the code that I wrote(with --complement option) would be appreciated.

P.S. As an initial try using awk, I tried to split the input file into columns using nothing as field seperator like

Code:

awk -F=""

but the version of awk that I have isn't interpreting it correctly.(I know it is pretty much screwed up if I have old versions of commands without features . But what to do. Our IT team isn't willing to update to latest linux )

Thanks a lot
Regards
VNR