Shell脚本read用法实现

read [-options] [variable...]

#!/bin/bash

# read-integer

echo -n "Please enter an integer -> "
read int

if [[ "$int" =~ ^-?[0-9]+$ ]]; then
        if [ "$int" -eq 0 ]; then
                echo "$int is zero."
        else
                if [ "$int" -lt 0 ]; then
                        echo "$int is negative."
                else
                        echo "$int is positive"
                fi
        fi
        if [ $((int % 2)) -eq 0 ]; then
                echo "$int is even."
        else
                echo "$int is odd."
        fi
else
        echo "Input value is not an integer." >&2
        exit 1
fi

[sysadmin@ansible bin]$ cat read1
#!/bin/bash

#read-multiple

echo -n "Enter one or more values > "
read var1 var2 var3 var4 var5

echo "var1 = '$var1'"
echo "var2 = '$var2'"
echo "var3 = '$var3'"
echo "var4 = '$var4'"
echo "var5 = '$var5'"
[sysadmin@ansible bin]$ read1
Enter one or more values > 1 2 3 4 5
var1 = '1'
var2 = '2'
var3 = '3'
var4 = '4'
var5 = '5'

[sysadmin@ansible bin]$ cat read1
#!/bin/bash

#read-multiple

echo -n "Enter one or more values > "
read var1 var2 var3 var4 var5

echo "var1 = '$var1'"
echo "var2 = '$var2'"
echo "var3 = '$var3'"
echo "var4 = '$var4'"
echo "var5 = '$var5'"
[sysadmin@ansible bin]$ read1
Enter one or more values > a
var1 = 'a'
var2 = ''
var3 = ''
var4 = ''
var5 = ''
[sysadmin@ansible bin]$ read1
Enter one or more values > a b c d e f g
var1 = 'a'
var2 = 'b'
var3 = 'c'
var4 = 'd'
var5 = 'e f g'
[sysadmin@ansible bin]$

[sysadmin@ansible bin]$ cat read2
#!/bin/bash

#read-multiple

echo -n "Enter one or more values > "
read

echo "REPLY = '$REPLY'"
[sysadmin@ansible bin]$ read2
Enter one or more values > a b c d
REPLY = 'a b c d'
[sysadmin@ansible bin]$

[sysadmin@ansible bin]$ cat read2
#!/bin/bash

#read-single

read -p "Enter one or more values > "

echo "REPLY = '$REPLY'"
[sysadmin@ansible bin]$ read2
Enter one or more values > a
REPLY = 'a'
[sysadmin@ansible bin]$

[sysadmin@ansible bin]$ cat readpass
#!/bin/bash

#read-pass

if read -t 10 -sp "Enter password > " passwd; then
        echo -e "\nSecret passphrase = '$passwd'"
else
        echo -e "\nInput timed out" >&2
        exit 1
fi
[sysadmin@ansible bin]$ readpass
Enter password >
Secret passphrase = 'abcdef'
[sysadmin@ansible bin]$

[sysadmin@ansible bin]$ cat readdefault
#!/bin/bash

#read-default

read -e -p "What is your user name? " -i $USER
echo "You answered: '$REPLY'"
[sysadmin@ansible bin]$ readdefault
What is your user name? sysadmin
You answered: 'sysadmin'
[sysadmin@ansible bin]$

[sysadmin@ansible bin]$ cat read-ifs
#!/bin/bash

# read-ifs

FILE=/etc/passwd

read -p "Enter a user > " user_name

file_info="$(grep "^$user_name:" $FILE)"

if [ -n "$file_info" ]; then
        IFS=":" read user pw uid gid name home shell <<< "$file_info"
        echo "User =            '$user'"
        echo "UID =             '$uid'"
        echo "GID =             '$gid'"
        echo "Full Name =       '$name'"
        echo "Home Dir =        '$home'"
        echo "Shell =           '$shell'"
else
        echo "No such user '$user_name'" >&2
        exit 1
fi
[sysadmin@ansible bin]$ read-ifs
Enter a user > jticnoc
User =          'jticnoc'
UID =           '2099'
GID =           '2099'
Full Name =     ''
Home Dir =      '/home/jticnoc'
Shell =         '/bin/bash'
[sysadmin@ansible bin]$

[sysadmin@ansible bin]$ cat read-validate
#!/bin/bash

#read-validate

invalid_input () {
        echo "Invalid input '$REPLAY'" >&2
        exit 1
}

read -p "Enter a single item > "

# input is null
[[ -z "$REPLY" ]] && invalid_input

# input is multi items
(( "$(echo "$REPLY" |wc -w)" > 1 )) && invalid_input

# input filename is valid
if [[ "$REPLY" =~ ^[-[:alnum:]\._]+$ ]]; then
        echo "'$REPLY' is a valid filename."
        if [[ -e "$REPLY" ]]; then
                echo "And file '$REPLY' exists."
        else
                echo "However, file '$REPLY' does not exist."
        fi

        # input is float
        if [[ "$REPLY" =~ ^-?[[:digit:]]*\.[[:digit:]]+$ ]]; then
                echo "'$REPLY' is a floating point number."
        else
                echo "'$REPLY' is not a floating point number."
        fi

        # input is int
        if [[ "$REPLY" =~ ^-?[[:digit:]]+$ ]]; then
                echo "'$REPLY' is an integer."
        else
                echo "'$REPLY' is not an integer."
        fi
else
        echo "The string '$REPLY' is not a valid filename."
fi
[sysadmin@ansible bin]$

[sysadmin@ansible bin]$ cat read-menu
#!/bin/bash

#read-menu

clear
echo "
Please Select:

1.Display System Information
2.Display Disk Space
3.Display Home Space Utilization
4.Quit
"
read -p "Enter selection [0-3] > "

if [[ "$REPLY" =~ ^[0-3]$ ]]; then
        if [[ "$REPLY" == 0 ]]; then
                echo "Program terminated."
                exit
        fi

        if [[ "$REPLY" == 1 ]]; then
                echo "Hostname: $HOSTNAME"
                uptime
                exit
        fi

        if [[ "$REPLY" == 2 ]]; then
                df -h
                exit
        fi

        if [[ "$REPLY" == 3 ]]; then
                if [[ "$(id -u)" -eq 0 ]]; then
                        echo "Home Space Utilization (ALL Users)"
                        du -sh /home/*
                else
                        echo "Home Space Utilizaion ($USER)"
                        du -sh "$HOME"
                fi
                exit
        fi
else
        echo "Invalid entry." >&2
        exit 1
fi