Programmatically execute vim commands?

I'm interested in setting up a TDD environment for developing Vim scripts and rc files. As a simple example, say I want to have vim insert 8 spaces when I press the tab key. I would set up a script that did the following:

• Launch vim using a sandboxed .vimrc file
• press i
• press tab
• press esc
• press :w test_out
• assert that test_out contains ' '

by the default config in vim, this would fail. However, once I add 开发者_C百科set expandtab to my .vimrc file, the test will pass.

How do I programmatically issue these commands? vim -c <commands> is close, but seems to only work for ex mode commands. Any suggestions? This question seem to be thoroughly google-proof.

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You can try vim -S <script in> and, for your convenience, the opposite vim -w <script out>.

For more details on these options check VIM's documentation for the -s and -w arguments.

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Is using vim a requirement? If it isn't you are using the wrong tool for the job, sed might be more appropriate.

But if you must, you can do it with vim anyway, just call it ex

#!/bin/sh
# insert a tab as the first character of test_out
ex test_out <<EOF
s/^/^I/
wq
EOF

if [ `od -c test_out | awk 'NR == 1 {print $2}'` != '\t' ] ; then
    echo "assertion failed"; exit 1;
fi

Where ^I is actually a Tab. Although this is a very odd approach.