Introduction to the position variables of special variables in shell programming _linux shell

1. Get the file name of the current script, including the path.

Copy Code code as follows:

#写一个测试脚本
Vim test.sh
#内容如下
Dirname$0
Basename$0
#执行一下
bash$ (PWD)/test.sh
#输出如下
/home/jane
test.sh

2. $n get the nth parameter of the current execution script, n=1..9,$0, for the current script name. If n is greater than 9, use ${10}

Copy Code code as follows:

Echo ' Echo ' $ (seq-s "$" 1 5|sed ' s/1/$1/') > test_n.sh
cattest_n.sh
#内容如下
#echo $ $ $ $
bashtest_n.sh arg1 AGR2 Arg3
#输出内容:
#arg1 AGR2 Arg3

3, $* get all the parameters of the script

Copy Code code as follows:

Echo ' echo $* ' >test_*.sh
cattest_*.sh
#内容如下:
#echo $*
Bashtest_*.sh 1 2 3
#输出:
#1 2 3

4, $# get the number of all the parameters of the script

Copy Code code as follows:

Echo ' echo $# ' >test_j.sh
cattest_j.sh
#内容如下:
#echo $#
Bashtest_j.sh 1 2 3
#输出:
#3