[unix] Create text file and fill it using bash

I need to create a text file (unless it already exists) and write a new line to the file all using bash.

I'm sure it's simple, but could anyone explain this to me?

#!/bin/bash
file_location=/home/test/$1.json
if [ -e $policy ]; then
  echo "File $1.json already exists!"
else
  cat > $file_location <<EOF
{
      "contact": {
          "name": "xyz",
          "phonenumber":   "xxx-xxx-xxxx"
      }
    }
EOF
fi

This code checks if the given JSON file of the user is present in test home directory or not. If it's not present it will create it with the content. You can modify the file location and content according to your needs.

Assuming you mean UNIX shell commands, just run

echo >> file.txt

echo prints a newline, and the >> tells the shell to append that newline to the file, creating if it doesn't already exist.

In order to properly answer the question, though, I'd need to know what you would want to happen if the file already does exist. If you wanted to replace its current contents with the newline, for example, you would use

echo > file.txt

EDIT: and in response to Justin's comment, if you want to add the newline only if the file didn't already exist, you can do

test -e file.txt || echo > file.txt

At least that works in Bash, I'm not sure if it also does in other shells.

Your question is a a bit vague. This is a shell command that does what I think you want to do:

echo >> name_of_file

Creating a text file in unix can be done through a text editor (vim, emacs, gedit, etc). But what you want might be something like this

echo "insert text here" > myfile.txt

That will put the text 'insert text here' into a file myfile.txt. To verify that this worked use the command 'cat'.

cat myfile.txt

If you want to append to a file use this

echo "append this text" >> myfile.txt