Shell Special position variable ($0,$1$2,$*,$#,$$,$?,$@,${})

$ file name and path

$1,$2 parameter 1, parameter 2

$#     The number of arguments passed to the script or function

current shell process ID

judge execution succeeded or not 0 for success

[email protected] Pass all parameters of a script or function

$*     Pass all parameters of a script or function

${}

Note: [Email protected] and the $* 's All Pass all parameters of a script or function. When enclosed by double quotation marks , the two have the following differences

[email protected] shell]# cat 007.sh

#!/bin/bash

For var in " [email protected] "

Do

echo "$var"

Done

[[Email protected] shell]# sh 007.sh feng cx Xiao

Feng

Cx

Xiao

[email protected] shell]# cat 007.sh

#!/bin/bash

For Var in "$*"

Do

echo "$var"

Done

[[Email protected] shell]# sh 007.sh feng cx Xiao

Feng Cx Xiao

$var and ${var} Differences

such as: When you want to display variable values with random characters

Echo $var _ AA $var will use the _aa later as part of the variable.

Echo ${var}_aa ${var} does not use the following _aa as part of a variable

This article is from the "Feng" blog, make sure to keep this source http://fengxiaoli.blog.51cto.com/12104465/1952185

Shell Special position variable ($0,$1$2,$*,$#,$$,$?,[email protected], ${})