Please always tell us what operating system and shell you're using when you start a new thread in the Shell Programming and Scripting forum. Many of the commands you're using in your bash script will behave differently on different operating systems. It is much easier to make suggestions that will work in your environment if we know what environment you're using.

When I run your script in a directory containing two files (one named problem and one named tester) and enter either of those names when prompted, I get the output:

Code:

total 24
-rw-r--r--  1 dwc  staff  1077 Jan 30 22:34 problem
-rwxr-xr-x  1 dwc  staff   457 Jan 30 23:34 tester
This will print out the first two columns of the inputted file in this directory
Enter filename found in this directory
problem
awk: illegal field $(), name "input"
 input record number 1, file problem
 source line number 1

When I enter any other value at the prompt, I get the output:

Code:

total 24
-rw-r--r--  1 dwc  staff  1077 Jan 30 22:34 problem
-rwxr-xr-x  1 dwc  staff   457 Jan 30 23:34 tester
This will print out the first two columns of the inputted file in this directory
Enter filename found in this directory
unknown
awk: can't open file unknown
 source line number 10
awk: can't open file unknown
 source line number 8

where unknown is whatever string I entered when prompted.

This is what I got when using bash and awk on macOS Mojave version 10.14.2. Different versions of awk might give you different diagnostic messages or might always treat the expression in your awk if statement:

Code:

if($input == echo$(ls))

as if it had been written as:

Code:

if($0 == $0)

(because you have defined the shell variable input by your bash read statement, but you have not defined a variable named input in your awk script. And using an undefined variable in an awk script causes it to be treated as either an empty string (when a string is expected) or as 0 (when a number is expected). Since none of the awk variables in your awk if statement are defined, I would expect that input will be treated as 0 (because a field number is expected after a dollar sign in awk), echo will be evaluated as an empty string because you are concatenating two strings (whatever echo expands to and whatever $(ls) expands to) and since ls expanded to an empty string on my version of awk I got a syntax error. If the code you showed us does print the 1st two columns from each line of a file in the currrent directory when you enter the name of a file in the current directory, apparently ls expanded to a 0 in your version of awk. In that case comparing the entire contents of any input line ($0) to itself ($(0)) will always yield true and print the 1st two fields of each line of the file using <tab> as a separator in the output.

No matter what version of awk you use, if you invoke it with one pathname operand and that pathname does not name an existing file, you will get an error message similar to the one I specified above or the one you alluded to in question 1 in post #1 in this thread.

Since you didn't really give us a definition of what you are trying to do with your script, I can only make wild guesses. If what I am guessing is correct, there is no reason to use awk at all. It can all be done in bash (or any shell that conforms to the POSIX standards) with something like:

Code:

#!/bin/bash

# This script provides a long listing of the current directory and asks the user
# to end the name of one of the files in the directory.  If the name of a file
# in the current directory is given, the first two fields on each line will be
# printed separated by a <tab> character.  Otherwise a diagnostic message will
# be printed.

# Clear the screen.
clear

# Provide a long listing of the files in the current directory.
ls -l

# Prompt for and read the name of a file to be processed.
echo 'This will print out the first two columns of the inputted file in this directory'
printf 'Enter the filename of a regular file found in this directory: '
read input

if [ -f "$input" ]
then	# The name of an existing regular file was given.  Print the first two fields.
	while read -r field1 field2 rest
	do	printf '%s\t%s\n' "$field1" "$field2"
	done < "$input"
else	# The name given does not name an existing file.
	echo "file \"$input\" not in this Directory"
	exit 1
fi

Note that I only tested for the presence of a regular file. Trying to read a directory or most other file types using the read utility isn't something you're ready to try handling yet.

The shell if statement in the above code could be replaced by a printf piped into an awk script, but it would be considerably more complicated than the above shell script.

Is this approximately what you were trying to do?