How to exit with an error code from nano

exit codenano

When using vim for “replying” to some program – typically git – it can be useful to deliberate exit with error, to abort the entire action that opened the window. Like

$ git commit -a
# vim opens, showing me the staged files and asking for a commit message
# oops, I see some stuff staged that wasn't supposed to be committed
:cq     # exit vim with nonzero exit code

This will prevent git from actually doing the commit.

Now unfortunately, some machines have nano configured as the default editor, so I occasionally find myself in that editor and correspondingly helpless.

What I've done for now was: log in with another ssh session and killall editor.

Is there a way to do the same thing from within nano itself, corresponding to vim's :cq?

Best Answer

This is what I can do in interactive sh (or bash etc.) with job control:

I can suspend nano with Ctrl+Z (^Z). Note: if the message is Suspension is not enabled then I need to press Alt+Z (M-Z) to enable. As far as I know these are default keybindings in nano.

If the command was nano || foo then foo will be triggered immediately.

Now I'm back in the shell with nano as a job (see jobs). kill %% will send a signal to it, still nano won't exit yet. I need to fg after sending the signal, only then nano terminates.

Not as fast as vim's :cq but still without additional SSH session.

Related Solutions

Getting ROBOCOPY to return a “proper” exit code

As per here, Robocopy has the following exit code bits that make up the exit code:

0×10 Serious error. Robocopy did not copy any files. This is either a usage error or an error due to insufficient access privileges on the source or destination directories.

0×08 Some files or directories could not be copied (copy errors occurred and the retry limit was exceeded). Check these errors further.

0×04 Some Mismatched files or directories were detected. Examine the output log. Housekeeping is probably necessary.

0×02 Some Extra files or directories were detected. Examine the output log. Some housekeeping may be needed.

0×01 One or more files were copied successfully (that is, new files have arrived).

0×00 No errors occurred, and no copying was done. The source and destination directory trees are completely synchronized.

Just add if/else statements that EXIT /B 0 when the return value is 1 or maybe 0, and EXIT /B 1 otherwise. Even if files might have been copied, there's something wrong that would need manual intervention.

Linux – exit code 128, what’s the reason

There is nothing within Bash documentation that says 128 is the required invalid exit code.

Bash itself returns the exit status of the last command executed, unless a syntax error occurs, in which case it exits with a non-zero value.

The last command is the bash builtin exit (from man page)

exit [n]

Cause the shell to exit with a status of n. If n is omitted, the exit status is that of the last command executed.

Checked specification for WEXITSTATUS.

WEXITSTATUS(stat_val)

If the value of WIFEXITED(stat_val) is non-zero, this macro evaluates to the low-order 8 bits of the status argument that the child process passed to _exit() or exit(), or the value the child process returned from main().

So exit is restricted to an 8 bit integer ( 0 - 255 ), so -1 would be 255. Exit only understands an integer argument and not floats, so it's likely kicking out a default -1.

bash$ echo $BASH_VERSION
4.1.10(4)-release

bash$ exit foo
exit
bash: exit: foo: numeric argument required
$ echo $?    
255

bash$ exit 2
exit
$ echo $?
2

bash$ exit -2
exit
$ echo $?
254

Best Answer

Related Solutions

Getting ROBOCOPY to return a “proper” exit code

Linux – exit code 128, what’s the reason

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