*nix, *bsd, etc basic `tput` color setup

Question

My goal with the below piece of POSIX shell code was to address the more platforms the better with shell tput colors. With this code, I now start all of my scripts, and so it's time to review it for some things I overlooked, did not think of too well, and such. Note: I start my scripts with set -u, which is why I set all empty in unspecified cases. Thanks.

---

#!/bin/sh
set -u
if tput setaf > /dev/null 2>&1; then
 # Linux-like
 tput_number_of_colors=$(tput colors 2> /dev/null)
 tput_bold=$(tput bold 2> /dev/null)
 tput_reset=$(tput sgr0 2> /dev/null)
 tput_cmd_set_fg_color='tput setaf'
elif tput AF > /dev/null 2>&1; then
 # BSD-like
 tput_number_of_colors=$(tput Co 2> /dev/null)
 tput_bold=$(tput md 2> /dev/null)
 tput_reset=$(tput me 2> /dev/null)
 tput_cmd_set_fg_color='tput AF'
else
 # Console-like
 tput_number_of_colors=2
 tput_cmd_set_fg_color=
 tput_bold=
 tput_reset=
fi
tput_test ()
{
 [ -n "$tput_number_of_colors" ] && [ -n "$tput_bold" ] && [ -n "$tput_reset" ] &&
 { [ "$tput_number_of_colors" -ge 8 ] && printf '%s' "$tput_bold" && $tput_cmd_set_fg_color 1; } > /dev/null 2>&1
}
if tput_test; then
 color_red=$tput_bold$($tput_cmd_set_fg_color 1)
 color_green=$tput_bold$($tput_cmd_set_fg_color 2)
 color_yellow=$tput_bold$($tput_cmd_set_fg_color 3)
 color_blue=$tput_bold$($tput_cmd_set_fg_color 4)
 color_magenta=$tput_bold$($tput_cmd_set_fg_color 5)
 color_cyan=$tput_bold$($tput_cmd_set_fg_color 6)
 color_white=$tput_bold$($tput_cmd_set_fg_color 7)
else
 color_red=; color_green=; color_yellow=; color_blue=; color_magenta=; color_cyan=; color_white=
fi

Answer 1

Self-review

Since no one replied thus far, I decided to re-think and re-write the code myself this morning.

---

terminfo (*nix) vs termcap (*bsd)

I never really thought about how important to make note of this actually is. For searching info online, one needs to know these keywords. So, I added them as comments.

Structure into functions

I believe this code should be structured into suitable functions where available.

Find a way for an exit code from those functions

It's needed to simply chain (&&) the commands like tput_bold=$(tput bold 2> /dev/null) && tput_reset=$(tput sgr0 2> /dev/null) in order for the imagined functions to return a reliable exit code.

The most basic test missing

command -v tput was missing in my code, which is remedied now.

No unset variables

Since I use set -u in my scripts, it's necessary to set variables empty in case of failure. This feature has been enhanced.

---

Modified code

#!/bin/sh
set -u
tput_setup_nix ()
{
 # terminfo
 tput_cmd_set_fg_color='tput setaf'
 tput_number_of_colors=$(tput colors 2> /dev/null) &&
 tput_bold=$(tput bold 2> /dev/null) &&
 tput_reset=$(tput sgr0 2> /dev/null)
}
tput_setup_bsd ()
{
 # termcap
 tput_cmd_set_fg_color='tput AF'
 tput_number_of_colors=$(tput Co 2> /dev/null) &&
 tput_bold=$(tput md 2> /dev/null) &&
 tput_reset=$(tput me 2> /dev/null)
}
tput_setup_none ()
{
 # no unset variables
 tput_cmd_set_fg_color=
 tput_number_of_colors=
 tput_bold=
 tput_reset=
}
if command -v tput > /dev/null 2>&1; then
 if tput setaf > /dev/null 2>&1; then
 if ! tput_setup_nix; then tput_setup_none; fi
 elif tput AF > /dev/null 2>&1; then
 if ! tput_setup_bsd; then tput_setup_none; fi
 else
 tput_setup_none
 fi
else
 tput_setup_none
fi
tput_capability_test ()
{
 [ -n "$tput_cmd_set_fg_color" ] && [ -n "$tput_number_of_colors" ] && [ -n "$tput_bold" ] && [ -n "$tput_reset" ] &&
 [ "$tput_number_of_colors" -ge 8 ] && { $tput_cmd_set_fg_color 1 && printf '%s' "$tput_bold$tput_reset"; } > /dev/null 2>&1
}
if tput_capability_test; then
 color_red=$tput_bold$($tput_cmd_set_fg_color 1)
 color_green=$tput_bold$($tput_cmd_set_fg_color 2)
 color_yellow=$tput_bold$($tput_cmd_set_fg_color 3)
 color_blue=$tput_bold$($tput_cmd_set_fg_color 4)
 color_magenta=$tput_bold$($tput_cmd_set_fg_color 5)
 color_cyan=$tput_bold$($tput_cmd_set_fg_color 6)
 color_white=$tput_bold$($tput_cmd_set_fg_color 7)
else
 color_red=
 color_green=
 color_yellow=
 color_blue=
 color_magenta=
 color_cyan=
 color_white=
fi

• Toby Speight: I don't see how the command -v tput adds anything, except complexity. If there's no available tput command, then we get error return from trying to execute it. Also, you can simplify if ! tput_setup_nix; then tput_setup_none; fi to simple tput_setup_nix || tput_setup_none.
• Vlastimil Burián: @TobySpeight Correct, command -v did not add anything.

Answer 2

2022 review

I found myself time for another self-review now, two years later.

Main features

• Simplified code, better readability.

• Removed unnecessary tests.

• Shortened code, rather unimportant.

---

Modified code

# Linux uses terminfo; BSD uses termcap; the null command (:) ignores everything after
tput_init_linux () { set_fg_color='tput setaf'; reset_color=$(tput sgr0 2>/dev/null); }
tput_init_bsd () { set_fg_color='tput AF'; reset_color=$(tput me 2>/dev/null); }
tput_init_none () { set_fg_color=':'; reset_color=; }
# This routine prepares `tput` on Linux and BSD and no color console
if tput setaf >/dev/null 2>&1; then tput_init_linux || tput_init_none;
elif tput AF >/dev/null 2>&1; then tput_init_bsd || tput_init_none;
else tput_init_none; fi
no_color () { printf '%s' "$reset_color"; }
colorize ()
{
 case "1ドル" in
 (red) $set_fg_color 1 ;;
 (green) $set_fg_color 2 ;;
 (yellow) $set_fg_color 3 ;;
 (blue) $set_fg_color 4 ;;
 (magenta) $set_fg_color 5 ;;
 (cyan) $set_fg_color 6 ;;
 (white) $set_fg_color 7 ;;
 (*) printf '%s\n' "This color ('1ドル') is not supported. Quitting!" >&2; exit 1 ;;
 esac
}
color_red=$(colorize red)
color_green=$(colorize green)
color_yellow=$(colorize yellow)
color_blue=$(colorize blue)
color_magenta=$(colorize magenta)
color_cyan=$(colorize cyan)
color_white=$(colorize white)
color_none=$(no_color)