Append file contents to the bottom of existing file in Bash

Question

Possible Duplicate:
Shell script to append text to each file?
How to append output to the end of text file in SHELL Script?

I'm trying to work out the best way to insert api details into a pre-existing config. I thought about using sed to insert the contents of the api text file to the bottom of the config.inc file. I've started the script but it doesn't work and it wipes the file.

#!/bin/bash

CONFIG=/home/user/config.inc
API=/home/user/api.txt

sed -e "\$a $API" > $CONFIG

What am I doing wrong?

Solution

This should work:

 cat "$API" >> "$CONFIG"

You need to use the >> operator to append to a file. Redirecting with > causes the file to be overwritten. (truncated).

Comments

[shellbye]

For single string, use echo like this echo "export JAVA_HOME=/usr/lib/jvm/jdk1.8.0_112" >> ~/.bashrc

[Hans Wouters]

Why echo instead of cat?

[William Pursell]

cat writes the contents of the named files to stdout. echo writes the arguments to stdout. They do different things.

[PT Huynh]

Should use 'more' instead of 'cat' as cat will spawn a new process.

[William Pursell]

@PTHuynh more is a bad choice. The purpose of more is to buffer output to a tty and break it up into sections for interactive human consumption. There is nothing interactive about writing to a file. If some shell has more as a builtin but not cat is an implementation detail.