Colorize zpool iostat output

[ethan-coe-renner]

Motivation and Context

Add colored output to zpool iostat to improve readability and allow users to quickly see relative sizes of various entries. Addresses #13168 by coloring space suffixes.

Description

Uses the interface introduced in #9340 to add color to zpool iostat.

If the ZFS_COLOR env variable is set, then the output of zpool iostat is colored as follows:

• Header rows are bold
• 0 space is colored gray
• Size suffixes are colored by order of magnitude
  • K is green
  • M is yellow
  • G is red
  • T is blue
  • P is magenta
  • E is cyan

Screenshots

How Has This Been Tested?

Manually tested

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.

[mcmilk]

When the output of zpool iostat is redirected to some file, then it will also print those ANSI key escapes ....
Maybe some check with isatty(int fd); could be done before?

Edit: libzfs_util.c has a isatty() check - so everything is fine with this. Please ignore this comment.

[mcmilk]

A rebase would be fine.
I see no errors within the code - but the tests should be triggered again.

[Low-power]

diff --git a/include/libzutil.h b/include/libzutil.h
index fe65265..a2938c7 100644
--- a/include/libzutil.h
+++ b/include/libzutil.h
@@ -173,9 +173,8 @@ struct zfs_cmd;
 #define	ANSI_GREEN	"\033[0;32m"
 #define	ANSI_YELLOW	"\033[0;33m"
 #define	ANSI_BLUE	"\033[0;34m"
-#define	ANSI_MAGENTA	"\033[0;34m"
-#define	ANSI_CYAN	"\033[0;34m"
-
+#define	ANSI_MAGENTA	"\033[0;35m"
+#define	ANSI_CYAN	"\033[0;36m"
 #define	ANSI_GRAY	"\033[0;37m"
 #define	ANSI_RESET	"\033[0m"
 #define	ANSI_BOLD	"\033[1m"

[Low-power]

Since this color scheme didn't use bold (bright) colors, some colors it uses may look too dark on a black background terminal; this actually reduces readability, especially for blue. Try finding the blue T in this example:

Therefore I suggest avoid using ANSI_BLUE without ANSI_BOLD.

[Low-power]

Therefore I suggest avoid using ANSI_BLUE without ANSI_BOLD.

This also applies to commit fb11b15 -- the renamed pathes in dark blue are extremely hard to read.