使用xshell securecrt 时，可以自定义颜色主题文件， 但是各个颜色块都代表什么意思呢？
搜索linux下文件颜色的含义，也没看到一个讲清楚的，比如说

蓝色表示目录；绿色表示可执行文件；红色表示压缩文件；浅蓝色表示链接文件；白色表示其他文件；黄色是设备文件，包括block, char, fifo。

但是内部原理是什么呢？现在想要改变xshell中目录的显示颜色，在ASNI颜色设置中 ，总共有16个颜色块， 哪一个代表目录的颜色呢？

如图

ASNI定义了几种基本颜色的编码

Black: \u001b[30m.
Red: \u001b[31m.
Green: \u001b[32m.
Yellow: \u001b[33m.
Blue: \u001b[34m.
Magenta: \u001b[35m.
Cyan: \u001b[36m.
White: \u001b[37m.
#30（黑色）、31（红色）、32（绿色）、 33（黄色）、34（蓝色）、35（洋红）、36（青色）、37（白色）

下面是个人理解， 有问题请指出
第一行每一个色块分别对应上面的8个编码，第二行分别对应加粗字体。

30颜色对应第一个色块， 37颜色对应第8个色块
例如， 把第一行第二个色块，改为白色，表示 31 编码的颜色，在xshell中将显示为白色。

第三方工具的设置ASNI颜色， 本质上就是把预定好这八种颜色，显示为其他颜色。
如果某个文件，颜色类型为39， 超出了这八种基本颜色，则显示为原本编码好的ASNI颜色

不同类型文件的ASNI颜色编码，运行这个命令可以直接看到

ln@ln-PC:~/1src/shell$  dircolors -p 
# Configuration file for dircolors, a utility to help you set the
# LS_COLORS environment variable used by GNU ls with the --color option.
# Copyright (C) 1996-2017 Free Software Foundation, Inc.
# Copying and distribution of this file, with or without modification,
# are permitted provided the copyright notice and this notice are preserved.
# The keywords COLOR, OPTIONS, and EIGHTBIT (honored by the
# slackware version of dircolors) are recognized but ignored.
# Below are TERM entries, which can be a glob patterns, to match
# against the TERM environment variable to determine if it is colorizable.
TERM Eterm
TERM ansi
TERM *color*
TERM con[0-9]*x[0-9]*
TERM cons25
TERM console
TERM cygwin
TERM dtterm
TERM gnome
TERM hurd
TERM jfbterm
TERM konsole
TERM kterm
TERM linux
TERM linux-c
TERM mlterm
TERM putty
TERM rxvt*
TERM screen*
TERM st
TERM terminator
TERM tmux*
TERM vt100
TERM xterm*
# Below are the color init strings for the basic file types. A color init
# string consists of one or more of the following numeric codes:
# Attribute codes:
# 00=none 01=bold 04=underscore 05=blink 07=reverse 08=concealed
# Text color codes:
# 30=black 31=red 32=green 33=yellow 34=blue 35=magenta 36=cyan 37=white
# Background color codes:
# 40=black 41=red 42=green 43=yellow 44=blue 45=magenta 46=cyan 47=white
#NORMAL 00 # no color code at all
#FILE 00 # regular file: use no color at all
RESET 0 # reset to "normal" color
DIR 01;34 # directory
LINK 01;36 # symbolic link. (If you set this to \'target\' instead of a
 # numerical value, the color is as for the file pointed to.)
MULTIHARDLINK 00 # regular file with more than one link
FIFO 40;33 # pipe
SOCK 01;35 # socket
DOOR 01;35 # door
BLK 40;33;01 # block device driver
CHR 40;33;01 # character device driver
ORPHAN 40;31;01 # symlink to nonexistent file, or non-stat\'able file ...
MISSING 00 # ... and the files they point to
SETUID 37;41 # file that is setuid (u+s)
SETGID 30;43 # file that is setgid (g+s)
CAPABILITY 30;41 # file with capability
STICKY_OTHER_WRITABLE 30;42 # dir that is sticky and other-writable (+t,o+w)
OTHER_WRITABLE 34;42 # dir that is other-writable (o+w) and not sticky
STICKY 37;44 # dir with the sticky bit set (+t) and not other-writable
# This is for files with execute permission:
EXEC 01;32
# List any file extensions like \'.gz\' or \'.tar\' that you would like ls
# to colorize below. Put the extension, a space, and the color init string.
# (and any comments you want to add after a \'#\')
# If you use DOS-style suffixes, you may want to uncomment the following:
#.cmd 01;32 # executables (bright green)
#.exe 01;32
#.com 01;32
#.btm 01;32
#.bat 01;32
# Or if you want to colorize scripts even if they do not have the
# executable bit actually set.
#.sh 01;32
#.csh 01;32
 # archives or compressed (bright red)
.tar 01;31
.tgz 01;31
.arc 01;31
.arj 01;31
.taz 01;31
.lha 01;31
.lz4 01;31
.lzh 01;31
.lzma 01;31
... etc

举例分析
DIR 01;34 # directory
定义了目录文件使用 34 编码， 在标准终端中， 显示颜色是蓝色

现在想要目录在xshell中的显示为绿色，由于目录颜色为34编码，对应第5个色块（30对应第一个色块）， 则在ASNI设置中点击 第一行第五个色块， 在色板中选中绿色， 那么目录文件将显示为绿色。

假如出现了例外，运行 dircolors -p 显示 DIR 01;35 # directory 那么目录的ASNI颜色是35 ， 则想要修改目录的显示颜色，则需要点 第一行第六个色块。

到这里终于可以明明白白的修改颜色显示了。

dircolors 命令实际操作的是环境变量 $LS_COLORS

下面是一个脚本文件，打印显示所有已定义的颜色规则

#!/bin/bash
# For LS_COLORS, print type and description in the relevant color.
IFS=:
for ls_color in $LS_COLORS; do
    color="${ls_color#*=}"
    type="${ls_color%=*}"
    # Add descriptions for named types.
    case "$type" in
    bd) type+=" (block device)" ;;
    ca) type+=" (file with capability)" ;;
    cd) type+=" (character device)" ;;
    di) type+=" (directory)" ;;
    do) type+=" (door)" ;;
    ex) type+=" (executable file)" ;;
    fi) type+=" (regular file)" ;;
    ln) type+=" (symbolic link)" ;;
    mh) type+=" (multi-hardlink)" ;;
    mi) type+=" (missing file)" ;;
    no) type+=" (normal non-filename text)" ;;
    or) type+=" (orphan symlink)" ;;
    ow) type+=" (other-writable directory)" ;;
    pi) type+=" (named pipe, AKA FIFO)" ;;
    rs) type+=" (reset to no color)" ;;
    sg) type+=" (set-group-ID)" ;;
    so) type+=" (socket)" ;;
    st) type+=" (sticky directory)" ;;
    su) type+=" (set-user-ID)" ;;
    tw) type+=" (sticky and other-writable directory)" ;;
    esac
    # Separate each color with a newline.
    if [[ $color_prev ]] && [[ $color != $color_prev ]]; then
        echo
    fi
    printf "\e[%sm%s\e[m " "$color" "$type"
    # For next loop
    color_prev="$color"
done
echo

运行这个脚本，可以看到不同类型的文件的显示效果不同。

参考链接 http://www.cnblogs.com/xlmeng1988/archive/2013/01/08/shell_color.html
http://blog.chinaunix.net/uid-26021340-id-3481924.html
https://askubuntu.com/questions/17299/what-do-the-different-colors-mean-in-ls