linux env /printenv/fw_printenv区别

1. fw_printenv（自己也可定义）： 可以打印出在uboot中设置的环境变量的值。

2. env/printenv 都是打印当系统环境变量。

   不同的是printenv不加参数和env一样，printenv可以打印指定名称的环境变量。


ENV(1)                           User Commands                          ENV(1)

NAME
       env - run a program in a modified environment

SYNOPSIS
       env [OPTION]... [-] [NAME=VALUE]... [COMMAND [ARG]...]

DESCRIPTION
       Set each NAME to VALUE in the environment and run COMMAND.

       -i, --ignore-environment
              start with an empty environment

       -u, --unset=NAME
              remove variable from the environment

       --help display this help and exit

       --version
              output version information and exit

       A mere - implies -i.  If no COMMAND, print the resulting environment.


PRINTENV(1)                      User Commands                     PRINTENV(1)

NAME
       printenv - print all or part of environment

SYNOPSIS
       printenv [VARIABLE]...
       printenv OPTION

DESCRIPTION
       Print the values of the specified environment VARIABLE(s).  If no VARIABLE is specified, print name and value pairs for them all.

       --help display this help and exit

       --version
              output version information and exit

       NOTE:  your shell may have its own version of printenv, which usually supersedes the version described here.  Please refer to your shellâs documentation for details about
       the options it supports.