利用cpio 可将文件或目录从文件库获取出来或将散列文件拷贝到文件库。cpio 的指令格式：
cpio –i[bcdmrtuv] [patterns]
cpio –o [abcv]
cpio –p [adlmuv][directory]
说明：cpio 共有三种基本模式，-o即copy-out 模式，将一组文件copy到一个文件库，-i 即copy-in 模式，读取文件库，并将其展开在当前目录。-p 能从某个目录读取所有文件（包括子目录到另一个目录），且不以archive(归档)的方式存放。
cpio 常配合shell使用。-o常用标准输入设备读取要copy 的文件名称，并将copy成的archive file 通过标准输出设备输出。一般利用输入/输出重定向或管道的原理，达到真正复制的功能。
（一）利用cpio备份：
[例1]
$ find temo –print | cpio –ocdv > /dev/rfd0135ds18
例: find . |cpio -co > ../initrd
将temp目录下的文件备份到软盘上。-o表示输出模式，-c生成一个带有头信息的文件。 -d表示按需要生成目录，-v表示命令执行时不断显示信息。用“>”把结果定向到软盘。
[例2]
$ ls |cpio –o >/usr/backup
将当前目录下的所有文件复制成backup archive file
[例3]
$ ls *.c | cpio –o>backup
复制工作目录中的所有的c程序.
[例4]
$ ls| cpio –p /usr/linfs/tempdir
复制当前工作目录下的文件到/usr/linfs/tempdir 目录，不生成archive file
（二）利用cpio 复原：
[例5]
$ cpio –icdv < /dev/rfd0135ds18
例： cpio -i < ../initrd将上层目录的initrd文件释放到当前文件夹
将软盘中的文件复原。-i告诉cpio把文件作为它的输入，-d按需要生成目录，-v显示执行时的所有信息，-c具有头文件格式。
[例6]
$ cpio –icdv "*stat.wp" < /dev/rfd0135ds18
仅复原*stat.wp的文件
[例7]
$ cpio –i </usr/linfs/old1 *.f
仅复原*.f 文件
序：
(gzip 压缩文件)
gzip 压缩文件对应的解压缩文件为gunzip。压缩后的文件名称为“.gz”。命令格式：
gzip filename
gunzip filename
I. Intro
1. A shell script contains commands that are executed as if you typed them in the terminal.
2. We'll be using Vim for this tutorial
a. Install Vim : sudo apt-get install vim
b. Vim Commands
1. i : insert mode
2. <ESC> : enter command mode
i. w : Save / Don't Exit
ii. wq : Save / Quit
iii. q! : Quit / Discard Changes
iv. w : Move to front of next word
v. b : Move backwards to front of word
vi. 0 : Move to start of line
vii. $ : Move to end of line
viii. G : Jump to last line
3. Move around with arrows
4. :set number : Displays line numbers
5. :syntax on : Syntax Highlighting
6. :set tabstop=2 : Spaces in tab
7. :set autoindent : Indent new lines
8. Save these in your home/~/.vimrc file
a. Find out what vimrc file you are using with this command in Vim :echo $MYVIMRC
3. Hello World Script
# The #! shebang tells the system the interpreter to use for the script
#!/bin/bash
# Comment
echo 'Hello World' # Print the string to the screen
a. To make it executable chmod 755 hello_world
b. Execute with ./hello_world
c. The numbers after chmod define who can do what with the file
d. The numbers represent the Owner, the Group and Everyone else
e. What the numbers mean
1. 7 : Read, Write & Execute
2. 6 : Read & Write
3. 5 : Read & Execute
4. 4 : Read Only
5. 3 : Write & Execute
6. 2 : Write Only
7. 1 : Execute Only
8. 0 : None
4. We define variables like this myName="Derek"
a. The variable name starts with a letter or _ and then can also contain numbers
b. The shell treats all variables as strings
c. When declaring a variable you can't have whitespace on either side of the =
d.
#!/bin/bash
declare -r NUM1=5 # Declare a constant
num2=4
# Use arithmetic expansion for adding
num3=$((NUM1+num2))
num4=$((NUM1-num2))
num5=$((NUM1*num2))
num6=$((NUM1/num2))
# Place variables in strings with $
echo "5 + 4 = $num3"
echo "5 - 4 = $num4"
echo "5 * 4 = $num5"
echo "5 / 4 = $num6"
echo $(( 5**2 ))
echo $(( 5%4 ))
# Assignment operators allow for shorthand arithmetic
# +=, -=, *=, /=
rand=5
let rand+=4
echo "$rand"
# Shorthand increment and decrement
echo "rand++ = $(( rand++ ))"
echo "++rand = $(( ++rand ))"
echo "rand-- = $(( rand-- ))"
echo "--rand = $(( --rand ))"
# Use Python to add floats
num7=1.2
num8=3.4
num9=$(python -c "print $num7+$num8")
echo $num9
# You can print over multiple lines with a Here Script
# cat prints a file or any string past to it
cat << END
This text
prints on
many lines
END
II. Functions
1. You can use functions to avoid the need to write duplicate code
2. Delete all code in Vim with gg then dG
3. #!/bin/bash
# Define function
getDate() {
# Get current date and time
date
# Return returns an exit status number between 0 - 255
return
}
getDate
# This is a global variable
name="Derek"
# Local variable values aren't available outside of the function
demLocal() {
local name="Paul"
return
}
demLocal
echo "$name"
# A function that receives 2 values and prints a sum
getSum() {
# Attributes are retrieved by referring to $1, $2, etc.
local num3=$1
local num4=$2
# Sum values
local sum=$((num3+num4))
# Pass values back with echo
echo $sum
}
num1=5
num2=6
# You pass atributes by separating them with a space
# Surround function call with $() to get the return value
sum=$(getSum num1 num2)
echo "The sum is $sum"
III. Conditionals / Input
1.
#!/bin/bash
# You can use read to receive input which is stored in name
# The p option says that we want to prompt with a string
read -p "What is your name? " name
echo "Hello $name"
read -p "How old are you? " age
# You place your condition with in []
# Include a space after [ and before ]
# Integer Comparisons: eq, ne, le, lt, ge, gt
if [ $age -ge 16 ]
then
echo "You can drive"
# Check another condition
elif [ $age -eq 15 ]
then
echo "You can drive next year"
# Executed by default
else
echo "You can't drive"
# Closes the if statement
fi
2. Extended integer test
#!/bin/bash
read -p "Enter a number : " num
if ((num == 10)); then
echo "Your number equals 10"
fi
if ((num > 10)); then
echo "It is greater then 10"
else
echo "It is less then 10"
fi
if (( ((num % 2)) == 0 )); then
echo " It is even"
fi
# You can use logical operators like &&, || and !
if (( ((num > 0)) && ((num < 11)) )); then
echo "$num is between 1 and 10"
fi
# && and || can be used as control structures
# Create a file and then if that worked open it in Vim
touch samp_file && vim samp_file
# If samp_dir doesn't exist make it
[ -d samp_dir ] || mkdir samp_dir
# Delete file rm samp_file
# Delete directory rmdir samp_dir
3. Testing strings
#!/bin/bash
str1=""
str2="Sad"
str3="Happy"
# Test if a string is null
if [ "$str1" ]; then
echo "$str1 is not null"
fi
if [ -z "$str1" ]; then
echo "str1 has no value"
fi
# Check for equality
if [ "$str2" == "$str3" ]; then
echo "$str2 equals $str3"
elif [ "$str2" != "$str3" ]; then
echo "$str2 is not equal to $str3"
fi
if [ "$str2" > "$str3" ]; then
echo "$str2 is greater then $str3"
elif [ "$str2" < "$str3" ]; then
echo "$str2 is less then $str3"
fi
# Check the file test_file1 and test_file2
file1="./test_file1"
file2="./test_file2"
if [ -e "$file1" ]; then
echo "$file1 exists"
if [ -f "$file1" ]; then
echo "$file1 is a normal file"
fi
if [ -r "$file1" ]; then
echo "$file1 is readable"
fi
if [ -w "$file1" ]; then
echo "$file1 is writable"
fi
if [ -x "$file1" ]; then
echo "$file1 is executable"
fi
if [ -d "$file1" ]; then
echo "$file1 is a directory"
fi
if [ -L "$file1" ]; then
echo "$file1 is a symbolic link"
fi
if [ -p "$file1" ]; then
echo "$file1 is a named pipe"
fi
if [ -S "$file1" ]; then
echo "$file1 is a network socket"
fi
if [ -G "$file1" ]; then
echo "$file1 is owned by the group"
fi
if [ -O "$file1" ]; then
echo "$file1 is owned by the userid"
fi
fi
4. With extended test [[ ]] you can use Regular Expressions
#!/bin/bash
read -p "Validate Date : " date
pat="^[0-9]{8}$"
if [[ $date =~ $pat ]]; then
echo "$date is valid"
else
echo "$date is not valid"
fi
5. # Read multiple values
#!/bin/bash
read -p "Enter 2 Numbers to Sum : " num1 num2
sum=$((num1+num2))
echo "$num1 + $num2 = $sum"
# Hide the input with the s code
read -sp "Enter the Secret Code" secret
if [ "$secret" == "password" ]; then
echo "Enter"
else
echo "Wrong Password"
fi
6. You can set what separates the values with IFS
#!/bin/bash
# Store the original value of IFS
OIFS="$IFS"
# Set what separates the input values
IFS=","
read -p "Enter 2 numbers to add separated by a comma" num1 num2
# Use the parameter expansion ${} to substitute any whitespace
# with nothing
num1=${num1//[[:blank:]]/}
num2=${num2//[[:blank:]]/}
sum=$((num1+num2))
echo "$num1 + $num2 = $sum"
# Reset IFS to the original value
IFS="$OIFS"
# Parameter expansion allows you to do this
name="Derek"
echo "${name}'s Toy"
# The search and replace allows this
samp_string="The dog climbed the tree"
echo "${samp_string//dog/cat}"
# You can assign a default value if it doesn't exist
echo "I am ${name:-Derek}"
# This uses the default if it doesn't exist and assigns the value
# to the variable
echo "I am ${name:=Derek}"
echo $name
7. Use case to when it makes more sense then if
#!/bin/bash
read -p "How old are you : " age
# Check the value of age
case $age in
# Match numbers 0 - 4
[0-4])
echo "To young for school"
;; # Stop checking further
# Match only 5
5)
echo "Go to kindergarten"
;;
# Check 6 - 18
[6-9]|1[0-8])
grade=$((age-5))
echo "Go to grade $grade"
;;
# Default action
*)
echo "You are to old for school"
;;
esac # End case
8. Ternary Operator performs different actions based on a condition
#!/bin/bash
can_vote=0
age=18
((age>=18?(can_vote=1):(can_vote=0)))
echo "Can Vote : $can_vote"
IV. Parameter Expansions and Strings
1. Strings
#!/bin/bash
rand_str="A random string"
# Get string length
echo "String Length : ${#rand_str}"
# Get string slice starting at index (0 index)
echo "${rand_str:2}"
# Get string with starting and ending index
echo "${rand_str:2:7}"
# Return whats left after A
echo "${rand_str#*A }"
V. Looping
1. While Loop
#!/bin/bash
num=1
while [ $num -le 10 ]; do
echo $num
num=$((num + 1))
done
2. Continue and Break
#!/bin/bash
num=1
while [ $num -le 20 ]; do
# Don't print evens
if (( ((num % 2)) == 0 )); then
num=$((num + 1))
continue
fi
# Jump out of the loop with break
if ((num >= 15)); then
break
fi
echo $num
num=$((num + 1))
done
3. Until loops until the loop is true
#!/bin/bash
num=1
until [ $num -gt 10 ]; do
echo $num
num=$((num + 1))
done
4. Use read and a loop to output file info
#!/bin/bash
while read avg rbis hrs; do
# printf allows you to use \n
printf "Avg: ${avg}\nRBIs: ${rbis}\nHRs: ${hrs}\n"
# Pipe data into the while loop
done < barry_bonds.txt
5. There are many for loop options. Here is the C form.
#!/bin/bash
for (( i=0; i <= 10; i=i+1 )); do
echo $i
done
6. We can cycle through ranges
#!/bin/bash
for i in {A..Z}; do
echo $i
done
7.
VI. Arrays
1. Bash arrays can only have one dimension and indexes start at 0
2. Messing with arrays
#!/bin/bash
# Create an array
fav_nums=(3.14 2.718 .57721 4.6692)
echo "Pi : ${fav_nums[0]}"
# Add value to array
fav_nums[4]=1.618
echo "GR : ${fav_nums[4]}"
# Add group of values to array
fav_nums+=(1 7)
# Output all array values
for i in ${fav_nums[*]}; do
echo $i;
done
# Output indexes
for i in ${!fav_nums[@]}; do
echo $i;
done
# Get number of items in array
echo "Array Length : ${#fav_nums[@]}"
# Get length of array element
echo "Index 3 length : ${#fav_nums[3]}"
# Sort an array
sorted_nums=($(for i in "${fav_nums[@]}"; do
echo $i;
done | sort))
for i in ${sorted_nums[*]}; do
echo $i;
done
# Delete array element
unset 'sorted_nums[1]'
# Delete Array
unset sorted_nums
VII. Positional Parameters
1. Positional parameters are variables that can store data on the command line in variable names 0 - 9
a. $0 always contains the path to the executed script
b. You can access names past 9 by using parameter expansion like this ${10}
2. Add all numbers on the command line
#!/bin/bash
# Print the first argument
echo "1st Argument : $1"
sum=0
# $# tells you the number of arguments
while [[ $# -gt 0 ]]; do
# Get the first argument
num=$1
sum=$((sum + num))
# shift moves the value of $2 into $1 until none are left
# The value of $# decrements as well
shift
done
echo "Sum : $sum"