echo：显示文本

NAME
       echo - display a line of text

SYNOPSIS
       echo [SHORT-OPTION]... [STRING]...
       echo LONG-OPTION

-n

[root@localhost doc]# echo -n
[root@localhost doc]# echo

[root@localhost doc]#

[root@localhost doc]# echo -n "this year is 2017,\n the day is Feb 11"
this year is 2017,\n the day is Feb 11[root@localhost doc]#

-e：文本开启转义符

[root@localhost doc]# echo "this year is 2017,\n the day is Feb 11"
this year is 2017,\n the day is Feb 11
[root@localhost doc]# echo -e "this year is 2017,\n the day is Feb 11"
this year is 2017,
 the day is Feb 11

printf：格式化并显示文本

PRINTF(1)                        User Commands                       PRINTF(1)

NAME
       printf - format and print data

SYNOPSIS
       printf FORMAT [ARGUMENT]...
       printf OPTION

[root@localhost doc]# printf "this year is 2017,the day is Feb 11"
this year is 2017,the day is Feb 11[root@localhost doc]#

file 判断文件类型

该命令用来识别文件类型，也可用来辨别一些文件的编码格式。它是通过查看文件的头部信息来获取文件类型，而不是像Windows通过扩展名来确定文件类型的。

NAME
     file - determine file type

SYNOPSIS
     file [-bchikLNnprsvz0] [--apple] [--mime-encoding] [--mime-type] [-e testname] [-F separator]
          [-f namefile] [-m magicfiles] file ...
     file -C [-m magicfiles]
     file [--help]

ELF：可执行链接文件

[rhel@localhost ~]$ file /bin/ls
/bin/ls: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.18, stripped

linux常用命令-echo/printf/file