My first bash at shell scripting (sorry...)

Daws · 03-21-2007, 02:42 PM

Hello everybody, today I thought I'd have a go at some shell scripting. This was my first go at a simple script:

Code:

#!/bin/bash

if [ -f "$1" ]; then
    shred -zvf "$1"
    rm -fv "$1"
elif [ -d "$1" ]; then
    cd "$1"
    find -type f -exec shred -zvf {} \;
    cd ..
    rm -rfv "$1"
else
    echo "File Does Not Exist"
fi

Well it worked, for one file or directory only. So after a bit of searching and a labourious skim through a scripting guide, I was under the impression that replacing $1 with $@ would make it work for multiple files.

Alas no. I get "Binary operator expected" errors. I think I may be interpreting these guidelines wrong but $@ was what I thought I wanted. Clearly not.

So my question is, what do I replace $1 with to make this script work with multiple files? (Assuming that's what I need to replace)

PS. I know this is a silly script and rather dangerous at that, while I appreciate alternatives methods, I want the script to work because it's a script, not because I desire to shred multiple files, if you know what I mean.

rjwilmsi · 03-21-2007, 02:48 PM

Use $* instead of $@ or do a loop like:
for arg do rm "$arg" done

osor · 03-21-2007, 02:50 PM

Quote:

Originally Posted by Daws

Hello everybody, today I thought I'd have a go at some shell scripting. This was my first go at a simple script:

Code:

#!/bin/bash

if [ -f "$1" ]; then
    shred -zvf "$1"
    rm -fv "$1"
elif [ -d "$1" ]; then
    cd "$1"
    find -type f -exec shred -zvf {} \;
    cd ..
    rm -rfv "$1"
else
    echo "File Does Not Exist"
fi

Well it worked, for one file or directory only. So after a bit of searching and a labourious skim through a scripting guide, I was under the impression that replacing $1 with $@ would make it work for multiple files.

Alas no. I get "Binary operator expected" errors. I think I may be interpreting these guidelines wrong but $@ was what I thought I wanted. Clearly not.

So my question is, what do I replace $1 with to make this script work with multiple files? (Assuming that's what I need to replace)

PS. I know this is a silly script and rather dangerous at that, while I appreciate alternatives methods, I want the script to work because it's a script, not because I desire to shred multiple files, if you know what I mean.

If you take look at “man test” you’ll find that test will take only one argument with the file testing flags (i.e., -f, -d, etc.). I’m afraid the only way to do what you’re asking is within a loop like so:

Code:

#!/bin/bash

for file in $@; do
    if [ -f "$file" ]; then
        shred -zvf "$file"
        rm -fv "$file"
    elif [ -d "$file" ]; then
        cd "$file"
        find -type f -exec shred -zvf {} \;
        cd ..
        rm -rfv "$file"
    else
        echo "File $file Does Not Exist"
    fi
done

Daws · 03-21-2007, 03:03 PM

Thank you very much. Nice speedy replies, (maybe record).

I'll probably see you later in my much anticipated thread "Help: I hosed my system with a silly script"

Cheers.

johngreenwood · 03-21-2007, 05:42 PM

Since we're doing first bash scripts, here is mine (I was going to do "Hello world" script, but it was too simple so I did that one in my head).

It's pretty basic, it asks for a device, then a mountpoint, if you want to specify a filesystem type, and if you want to mount read only, then mounts it and asks if you want to mount another. I wrote it with the help of the Advanced Bash Scripting Guide

I never use it, but I am keeping it because it was my first one.

Code:

#! /bin/bash
#
#
# Mount or unmount specified drives to specified mountpoints
# 

while getopts "VUh" Option
do
	case $Option in
		h) echo " "
		   echo "Mounting interactively mounts or umounts filesystems entered by user"
		   echo "Usage: amountscript [-VUh]"
		   echo "Options: -h print this help and exit"
		   echo "         -V print version and exit"
		   echo "	 -U run script in unmount mode "
		   echo " "
		   exit;;
		V) echo " "
		   echo "Mounting v0.3"
		   echo "Author J Greenwood"
		   echo "05/01/2007"
		   echo " "
		   exit;;
		U) if 
			[ "$UID" -ne "0" ]
		    then
			echo "Must be root to run this script"
			exit
		   fi 
		   echo "Running Mounting in unmount mode"
	           YN=y
		   while [ "$YN" = "y" ]	
		   do
			echo -n "Enter device identifier (eg. /dev/hda1): "
			read -e DEVICE
			umount $DEVICE
			echo -n "Unmount another? (y/n): "
			read -e YN
			if
				[ "$YN" = "y" ]
			 then
				 echo ""
			 else
				 exit
			fi
	  	   done
		exit;;
	esac
done


# Checks to see if you are root, if not you can't run the script

if
	[ "$UID" -ne "0" ]
 then
	echo "This script must be run as root"
	exit
fi

YN=y

# Keep looping until you say no to mount another
# Asks for information about the drive you want to mount
# And mounts it according to your answers

while [ "$YN" = "y" ]
do
	echo -n "Enter device identifier (eg. /dev/hda1): "
	read -e DEVICE
	echo -n "Enter mountpoint (eg. /mnt/hda1): "
	read -e MOUNTPOINT
	echo -n "Would you like to mount $DEVICE read-only? (y/n): "
	read -e RONLY
	echo -n "Would you like to specify a filesystem type? (y/n): "
	read -e FILETYPEYN
	
	
	if
		[ "$FILETYPEYN" = "y" ]
	 then
	  if
		[ "$RONLY" = "y" ]
	   then
		echo -n "Which filesystem does your device use? (eg. ext3): " 
		read -e FILETYPE
		mount -t $FILETYPE $DEVICE $MOUNTPOINT -o ro
	 elif	
		[ "$FILETYPEYN" = "y" ]
	  then
		echo -n "which filesystem does your device use? (eg. ext3): "
		read -e FILETYPE
		mount -t $FILETYPE $DEVICE $MOUNTPOINT
	  fi	
	fi
	
	if
		[ "$FILETYPEYN" = "n" ]
	 then
	  if
		[ "$RONLY" = "y" ]
	   then
		mount $DEVICE $MOUNTPOINT -o ro
	 elif
		 [ "$FILETYPEYN" = "n" ]
	   then
		 mount $DEVICE $MOUNTPOINT
	  fi
	fi

# Asks if you want to mount another device

	echo -n "Mount another? (y/n): "
	read -e YN

	if
		[ "$YN" = "y" ]
	 then	echo ""
	 else
		exit
	fi
done

exit

Daws · 03-21-2007, 06:20 PM

Nice script you got there, I too was thinking about ye olde "Hello World" but thought I'd rather do something semi-useful. My script was born out of a minor annoyance with the shred command. There is no option to recursively shred an entire directory tree.

EDIT: Woohoo 200!