Linux Scripting Tutorial (ii) scripting examples

Now let's discuss the general steps to write a script. Any good script should have help and input parameters. and write a pseudo script (framework.sh) that contains the framework structure that most scripts require, and is a very good idea. At this point, we only need to execute the copy command when writing a new script:

CP framework.sh MyScript

And then insert your own function.

Let's look at two more examples:

1, binary to decimal conversion

The script b2d converts the binary number (for example, 1101) to the corresponding decimal number. This is also an example of a mathematical operation using the expr command:

#!/bin/sh

# Vim:set sw=4 ts=4 et:

Help ()

{

Cat <

B2H-Convert binary to Decimal

USAGE:B2H [-h] Binarynum

OPTIONS:-H Help text

EXAMPLE:B2H 111010

would return 58

Help

Exit 0

}

Error ()

{

# Print an error and exit

echo "$"

Exit 1

}

Lastchar ()

{

# return ' last character ' a string in $rval

If [-Z "$"]; Then

# empty string

Rval= ""

Return

Fi

# WC puts some space behind the ' output ' is why we need sed:

Numofchar= ' Echo-n ' "$" | wc-c | Sed ' s///g '

# now cut out of the last Char

Rval= ' Echo-n ' "$" | Cut-b $numofchar '

}

Chop ()

{

# Remove the last character in string and return it in $rval

This paper url:http://www.bianceng.cn/os/linux/201410/45612.htm

If [-Z "$"]; Then

# empty string

Rval= ""

Return

Fi

# WC puts some space behind the ' output ' is why we need sed:

Numofchar= ' Echo-n ' "$" | wc-c | Sed ' s///g '

If ["$numofchar" = "1"]; Then

# only one char in string

Rval= ""

Return

Fi

numofcharminus1= ' expr $numofchar '-"1"

# now cut all but char:

Rval= ' Echo-n ' "$" | Cut-b 0-${numofcharminus1} '

}

While [-N ' $]; Todo

Case is in

-h) Help;shift 1;; # function Help is called

-Shift;break;; # End of options

-*) Error "error:no such option $. -H for help ";;

*) break;;

Esac

Done

# The main program

Sum=0

Weight=1

# One ARG must be given:

[-Z ' $] && Help

Binnum= "$"

Binnumorig= "$"

While [-N "$binnum"]; Todo

Lastchar "$binnum"

If ["$rval" = "1"]; Then

sum= ' expr ' $weight ' "+" "$sum"

Fi

# Remove the last position in $binnum

Chop "$binnum"

Binnum= "$rval"

weight= ' expr ' $weight ' "*" 2 '

Done

echo "Binary $binnumorig is decimal $sum"