How can I open a file read-only from command line with emacs/vi/vim

Question

Is there a way to tell emacs/vi/vim (from the command line) that I want to view the file in view-mode or read-only.

I know how to open a file as read only if emacs/vi/vim is already running.

Answer 1

For emacs:

emacs FILE --eval '(setq buffer-read-only t)'

There's no startup option to force read only.

Edit:
If you put this small function in your shell startup script (.bashrc for example) you can open a file read-only by typing ev file_to_view

ev() {
  emacs "$1" --eval '(setq buffer-read-only t)'
}

Answer 2

vim -R filename

Answer 3

view filename

Basically vim in read-only mode; simples!

Answer 4

vim -R <file>

allows writing with :w!

vim -c ":set nomodifiable"  <file>

Prevents the user from making any changes to the file in the buffer. But the user could make the buffer modifiable with :set modifiable

You could use

vim -c ":noremap q :q<cr>" -c ":map : <Esc>" -c ":set nomodifiable" <file>

to prevent the user from turning off the "nomodifiable", and allow the user to quit by pressing q. But, then the user can't enter command mode at all, which may or may not be what you want.

You could also open the file with the less command:

less <file>

To view the file in a vim-like environment but without the ability to change the file.

Answer 5

For emacs you can also use the view-mode.

emacsclient --create-frame --eval '(view-file "/tmp/EXAMPLE")'

or alternative inside a terminal:

emacsclient --nw --eval '(view-file "/tmp/EXAMPLE")'

Or you can use my wrapper script

Answer 6

Small follow-up to the accepted answer: You can alias this in your shell to reduce it to a single command. For example in bash you can put the following in your .bashrc:

emacsro() {
  emacs $1 --eval '(setq buffer-read-only t)'
}

(different shells will have different formats for doing this, but you get the idea)

I would have added this as a comment in reply to the accepted answer, but it didn't seem possible to have a multi-line "code" block in a comment, and (in bash anyway) the above code really does need to be on 3 separate lines.

Answer 7

sending a file to std out, may be acceptable given the size of the file

cat <file>  # dump whole file to stdout
head <file> # view the first few lines
tail <file> # view the last n lines