What is the difference between xterm-color & xterm-256color?
linux, macos, ncurses, terminal, xterm
Solution
`xterm-256color` describes Xterm with support for 256 colors enabled. `xterm-color` describes an older branch of Xterm that supports eight colors. `xterm-color` is not recommended, since it describes a variant of Xterm that’s less functional and that you’re not likely to be using. Usually you’ll want to use `xterm`, `xterm-16color` or `xterm-256color`.
In particular, `xterm-256color` is the default for Terminal starting with Mac OS X 10.7 Lion, with the next-best recommended values being `xterm-16color` or `xterm` (which only describes support for eight ANSI colors). Prior to 10.7, `xterm-color` was the default because Terminal didn’t support some critical features described by the recommended Xterm terminfo values, e.g., Background Color Erase (BCE), modern codes for switching main/alternate screens, 256 colors.
Sometimes people explicitly set `TERM` to `xterm-color` (as opposed to the recommended Xterm values) to disable functionality or work around incompatibilities between the available terminfo values on a particular computer and the terminal emulator being used.
Note that technically Terminal should have its own up-to-date terminfo values that describe exactly which features it supports, instead of using the values for Xterm, but:
- There isn’t one that’s up to date currently. `nsterm` represents Terminal’s ancestor from NeXTSTEP. Someone apparently has updated `nsterm` recently (sometime in the past couple of years), but I don’t know whether that has made its way into the ncurses distribution, and it may not be completely up to date with Terminal in 10.7.
- A number of programs and shell customization scripts explicitly check whether `$TERM` starts with (or is equal to) `xterm`. So some users would still need to know about using the recommended Xterm values with Terminal for compatibility with those.
If you’re not familiar with the terminfo system, take a look at the x-man-page://5/terminfo man page. Also, you can use the `infocmp` command to view the current terminfo settings or compare two different ones, e.g., `infocmp xterm-color xterm-256color` will show you all the differences between those two.
Problem
I've come across both `xterm-color` and `xterm-256color` as options when trying to set up my terminal program to use color - i.e. you can set your `TERM` environment variable to either one. I was wondering if anyone can describe the difference between the two? I've searched for documentation on my Ubuntu server as well as my mac but haven't found any. I've only been able to find various binary files in `/usr/share/terminfo`.