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Shell Script Cheat Sheet

Array​

  • Test code:
#!/bin/sh

array=(0 1 2 3)
echo $array
echo ${array[0]}
echo ${array[@]}
  • Output:
0
0
0 1 2

if​

  • Test code:
#!/bin/sh

val0=0
val1=1

#
if [ $val0 = 0 ]; then
	echo val0 = 0
elif [ $val0 = 1 ]; then
	echo val0 = 1
else
	echo otherwise
fi

# AND
if [ $val0 = 0 ] && [ $val1 != 1 ]; then
	echo true
else
	echo false
fi

# OR
if [ $val0 = 1 ] || [ $val1 = 1 ]; then
	echo true
else
	echo false
fi


file=foo.txt
dir=bar

# Existing of file or dir
if [ -f ${file} ] && [ -d ${dir} ]; then
	echo true
else
	echo false
fi
  • Output:
val0 = 0
false
true
false

for​

  • Test code:
#!/bin/sh

array=(0 1 2)

#
for i in `seq 10`; do
	echo $i
done

#
for j in ${array[@]}; do
	echo $j
done
  • Output:
1
2
3
4
5
6
7
8
9
10
0
1
2

Input​

  • Test code:
echo -n "input  > "
read VAR
echo "output > $VAR"
  • Output:
input  > hello
output > hello

Function​

  • Definition:
func() {
	echo hello
}

func_arg() {
	echo "arg1 = $1, arg2 = $2"
}