bash - 如何在 Bash 中转义颜色代码？

Question

我的 ~/.bashrc 中有一些颜色代码:

export LESS_TERMCAP_mb=$'\E[01;31m'       # begin blinking
export LESS_TERMCAP_md=$'\E[01;38;5;74m'  # begin bold
export LESS_TERMCAP_me=$'\E[0m'           # end mode

这为我的手册页增添了一些色彩。但是，当我使用 env 时，bash 仍然解释颜色代码:

$ env | grep LESS
LESS_TERMCAP_mb=
LESS_TERMCAP_md=
LESS_TERMCAP_me=

屏幕截图:

如何转义这些字符串以便可以将它们视为字符串文字？理想情况下类似于 env | escape_color_codes_somehow。

Answer 1

你可以这样做:

[STEP 101] $ echo ${!LESS_*}
LESS_TERMCAP_mb LESS_TERMCAP_md LESS_TERMCAP_me LESS_TERMCAP_se LESS_TERMCAP_so LESS_TERMCAP_ue LESS_TERMCAP_us
[STEP 102] $ for varname in ${!LESS_*}; do \
                 printf '%s=%q\n' $varname "${!varname}"; \
             done
LESS_TERMCAP_mb=$'\E[01;31m'
LESS_TERMCAP_md=$'\E[01;37m'
LESS_TERMCAP_me=$'\E[0m'
LESS_TERMCAP_se=$'\E[0m'
LESS_TERMCAP_so=$'\E[01;44;33m'
LESS_TERMCAP_ue=$'\E[0m'
LESS_TERMCAP_us=$'\E[00;32m'
[STEP 103] $

来自bash manual :

${parameter}

If the first character of parameter is an exclamation point (!), and parameter is not a nameref, it introduces a level of variable indirection. Bash uses the value of the variable formed from the rest of parameter as the name of the variable; this variable is then expanded and that value is used in the rest of the substitution, rather than the value of parameter itself. This is known as indirect expansion. If parameter is a nameref, this expands to the name of the variable referenced by parameter instead of performing the complete indirect expansion. The exceptions to this are the expansions of ${!prefix*} and ${!name[@]} described below.

<强> ${!prefix*}
<强> ${!prefix@}

Names matching prefix. Expands to the names of variables whose names begin with prefix, separated by the first character of the IFS special variable. When @ is used and the expansion appears within double quotes, each variable name expands to a separate word.