Shell Programming and Scripting

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

abcd
cdef
opqr

> delete_columns.sh file_name.txt 4 2

ac
ce
oq

# 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

 --complement

awk -F=""

awk -F"" '{print $1$3}'  infile

[root@dist unix]# cat file
abcd
cdef
opqr
[root@dist unix]# bash dele.sh 1 3
bd
df
pr
[root@dist unix]# bash dele.sh 2 4
ac
ce
oq
[root@dist unix]# cat dele.sh 
#!/bin/bash
while read i
do
     
     A=($(echo "${i}" | awk -F "" '{print $1,$2,$3,$4}'))
     a=$(((($(($1%2))==0))?0:1))
     b=$(((($(($2%2))==0))?2:3))
     echo "${A[$a]}${A[$b]}"
done <file
 
But this scipt  not comprehensive.

cut -c1,3 filename

cut -c1-5,7-15,19-84 filename