Shell built-in variables
【Purpose】
Learning shell built-in variables, example $0,$1,$2,$3,$#,$$,$*,$@,$-,$?
【Eevironment】
Ubuntu 16.04 bash env
【Procdeure】
Source code:
#!/bin/bash echo "shell args option"
echo "script name : $0"
echo "first args : $1"
echo "first args : $2"
echo "first args : $3" echo "------- \$# demonstration"
echo "args number: $#" echo "------- \$\$ demonstration"
echo "shell pid: $$" echo "------- \$* demonstration"
for i in "$*";do
echo $i
done echo "------- \$@ demonstration"
for i in "$@";do
echo $i
done echo "------- \$- demonstration"
echo $-
$ ./test.sh 1 2 3
shell args option
script name : ./test.sh
first args : 1
first args : 2
first args : 3
------- $# demonstration
args number: 3
------- $$ demonstration
shell pid: 12263
------- $* demonstration
1 2 3
------- $@ demonstration
------- $- demonstration
hB
vmuser@vmuser-virtual-machine:~/shell$ echo $?