Programming Forums > Script Programming > Bash / Shell Scripting

carlw · Apr 9th, 2012, 3:13 AM

Hi Guys, I'm working on a backup script for a university project. It needs a lot of work but I'm a BASH beginner.

My issue is: I'm trying to implement a solution where the user can just enter as the first argument, the name of the account to backup and as the second argument, f for a full backup or i for an incremental backup.

My code:

(Toggle Plain Text)

#!/bin/bash
SOURCEDIR="/home/$1"
TARGETDIR="/mnt/backup/"
OUTPUTFILE=$1backup-$(date +%Y%m%d).tar.gz
USERFILE="$1backup-\w+.tar.gz"


function incbackup {
tar -xvfz $TARGETDIR$USERFILE
tar -uvfz $TARGETDIR$USERFILE
}

function fullbackup {
tar -zcvpf $TARGETDIR$OUTPUTFILE $SOURCEDIR
}

if [ $2 = f ]; then
echo "Running Full Backup"
fullbackup
exit
        elif [ $2 = i ]; then
        echo "Running Incremental Backup"
        incbackup
        exit
                else
echo "usage ./backupscript [username] [f for full or i for incremental]"
fi
exit

The full backup works OK I think. The incremental has trouble locating the existing file - I tried to use regex in the variable "$USERFILE" - I gather this won't work?

Also I've been reading through the "man tar". I think my flags are OK?
tar -xvfz $TARGETDIR$USERFILE <- "extract, listing verbosely, the file with zip"
tar -uvfz $TARGETDIR$USERFILE <- "update listing verbosely, the file with zip"

How do my flags look?

Thanks in advance.

watael · Apr 9th, 2012, 9:45 AM

hi,

bash doesn't understand regexes (except inside double square brackets with tilde)
You have to use globs, and extended globs.
Check bash's man page for 'Pathname Expansion'

carlw · Apr 9th, 2012, 9:51 AM

Quote:

Originally Posted by watael

hi,

bash doesn't understand regexes (except inside double square brackets with tilde)
You have to use globs, and extended globs.
Check bash's man page for 'Pathname Expansion'

Thank you sir! I will read that tonight.

carlw · Apr 9th, 2012, 10:13 PM

OK so after reading: http://wiki.bash-hackers.org/syntax/expansion/globs

I changed my code:

(Toggle Plain Text)

#!/bin/bash
SOURCEDIR="/home/$1"
TARGETDIR="/mnt/backup/"
OUTPUTFILE=$1backup-$(date +%Y%m%d).tar.gz
USERFILE="$1backup-*.tar.gz"


function incbackup {
echo "Extracting Previous Backup"
tar -xvfz $TARGETDIR$USERFILE
echo "Updating Backup File"
tar -uvfz $TARGETDIR$USERFILE
}

function fullbackup {
tar -zcvpf $TARGETDIR$OUTPUTFILE $SOURCEDIR
}

if [ $2 = f ]; then
echo "Running Full Backup"
echo "-------------------"
fullbackup
exit
        elif [ $2 = i ]; then
        echo "Running Incremental Backup"
        echo "--------------------------"
        incbackup
        exit
                else
echo "usage ./backupscript [username] [f for full or i for incremental]"
fi
exit

I had done a full backup on the 8th of April and here's the output when I try to do an incremental today:

carl@ubuntubox:~$ ./backupscript carl i
Running Incremental Backup
--------------------------
Extracting Previous Backup
tar: /mnt/backup/carlbackup-20120408.tar.gz: Not found in archive
tar: Exiting with failure status due to previous errors
Updating Backup File
tar: Removing leading `/' from member names
/mnt/backup/carlbackup-20120408.tar.gz
carl@ubuntubox:~$

Do I need different flags or is it just not possible to use gzip when doing this type of incremental backup?

sharted · Apr 10th, 2012, 5:18 AM

I see several things you might benefit from considering:

1) you never check the return value of tar. You can do this by look at the $? variable;

2) I _think_ this error message might be because you have more than one backup in your /mnt/backup directory. When you pass more arguments to tar's extract capability it tries to extract subsequent files from the archive. I.e. imagine that

/mnt/backup/carlbackup-*.tar.gz

expands to

/mnt/backup/carlbackup-20120407.tar.gz /mnt/backup/carlbackup-20120408.tar.gz

tar will think you want to extract /mnt/backup/carlbackup-20120408.tar.gz from /mnt/backup/carlbackup-20120407.tar.gz. Given that this first file probably doesn't exist in the backup, you'll see the error message you see.

Of course, I could be completely wrong about this....

What's in your backup directory?

Have you tried doing what you want to do just at the command line?

hth

carlw · Apr 10th, 2012, 5:30 AM

Nice to hear from you again Sharted!

You're right, it doesn't work on the command line.

carl@ubuntubox:~$ cd /mnt/backup
carl@ubuntubox:/mnt/backup$ ls
backup-20120408.tgz carlbackup-20120408.tar.gz
carl@ubuntubox:/mnt/backup$ tar -xvfz carlbackup-20120408.tar.gz
tar: z: Cannot open: No such file or directory
tar: Error is not recoverable: exiting now
carl@ubuntubox:/mnt/backup$ tar -xvfz /mnt/backup/carlbackup-20120408.tar.gz
tar: z: Cannot open: No such file or directory
tar: Error is not recoverable: exiting now

OH WAIT I JUST FOUND THIS -- http://stackoverflow.com/questions/7...mmand-tar-xvfz
You leave the dash off the flags for some reason.
Also I need sudo - so I'll lookup how to implement sudo in to the script.

carlw · Apr 25th, 2012, 8:45 AM

oh no! Sharted is gone....I'll never get an answer!

Raybc · Apr 25th, 2012, 9:19 AM

Where's sharted? On a well-earned holiday?
I don't know much about archiving but the test command error is from the @ parameter expanding. Why not try

(Toggle Plain Text)

if [ "$2" = f ]; then
  echo "Running Full Backup"
  echo "-------------------"
  fullbackup
  exit
elif [ "$2" = i ]; then
  echo "Running Incremental Backup"
  echo "--------------------------"
  incbackup
  exit
else
  echo "usage ./backupscript [username] [f for full or i for incremental]"
fi

Putting quotes around the $2 returns a blank string even if $2 is not defined. You can drop the test on $1 altogether, for that part anyway.

Another alternative could be to put quotes around $@, or is it $*. One will give a word, the other a list of quoted words.

carlw · Apr 25th, 2012, 9:44 AM

A fellow Aussie! (I'm from Perth).
Thanks for your ideas, I'll have a think about them tomorrow when I get back to testing my script.
Carl

sharted · Apr 26th, 2012, 8:00 AM

Sorry guys, I'm in the middle of moving house. Gordon Bennett, it's a lot of work! I should be done by the middle of next week.

Apr 9th, 2012, 3:13 AM	#1
carlw Newbie Join Date: Mar 2012 Posts: 29 Rep Power: 0	BASH backup script Hi Guys, I'm working on a backup script for a university project. It needs a lot of work but I'm a BASH beginner. My issue is: I'm trying to implement a solution where the user can just enter as the first argument, the name of the account to backup and as the second argument, f for a full backup or i for an incremental backup. My code: (Toggle Plain Text) #!/bin/bash SOURCEDIR="/home/$1" TARGETDIR="/mnt/backup/" OUTPUTFILE=$1backup-$(date +%Y%m%d).tar.gz USERFILE="$1backup-\w+.tar.gz" function incbackup { tar -xvfz $TARGETDIR$USERFILE tar -uvfz $TARGETDIR$USERFILE } function fullbackup { tar -zcvpf $TARGETDIR$OUTPUTFILE $SOURCEDIR } if [ $2 = f ]; then echo "Running Full Backup" fullbackup exit elif [ $2 = i ]; then echo "Running Incremental Backup" incbackup exit else echo "usage ./backupscript [username] [f for full or i for incremental]" fi exit #!/bin/bash SOURCEDIR="/home/$1" TARGETDIR="/mnt/backup/" OUTPUTFILE=$1backup-$(date +%Y%m%d).tar.gz USERFILE="$1backup-\w+.tar.gz" function incbackup { tar -xvfz $TARGETDIR$USERFILE tar -uvfz $TARGETDIR$USERFILE } function fullbackup { tar -zcvpf $TARGETDIR$OUTPUTFILE $SOURCEDIR } if [ $2 = f ]; then echo "Running Full Backup" fullbackup exit elif [ $2 = i ]; then echo "Running Incremental Backup" incbackup exit else echo "usage ./backupscript [username] [f for full or i for incremental]" fi exit The full backup works OK I think. The incremental has trouble locating the existing file - I tried to use regex in the variable "$USERFILE" - I gather this won't work? Also I've been reading through the "man tar". I think my flags are OK? tar -xvfz $TARGETDIR$USERFILE <- "extract, listing verbosely, the file with zip" tar -uvfz $TARGETDIR$USERFILE <- "update listing verbosely, the file with zip" How do my flags look? Thanks in advance.

Apr 9th, 2012, 9:45 AM	#2
watael Hobbyist Programmer Join Date: Nov 2011 Posts: 148 Rep Power: 2	Re: BASH backup script hi, bash doesn't understand regexes (except inside double square brackets with tilde) You have to use globs, and extended globs. Check bash's man page for 'Pathname Expansion'

Apr 9th, 2012, 10:13 PM	#4
carlw Newbie Join Date: Mar 2012 Posts: 29 Rep Power: 0	Re: BASH backup script OK so after reading: http://wiki.bash-hackers.org/syntax/expansion/globs I changed my code: (Toggle Plain Text) #!/bin/bash SOURCEDIR="/home/$1" TARGETDIR="/mnt/backup/" OUTPUTFILE=$1backup-$(date +%Y%m%d).tar.gz USERFILE="$1backup-.tar.gz" function incbackup { echo "Extracting Previous Backup" tar -xvfz $TARGETDIR$USERFILE echo "Updating Backup File" tar -uvfz $TARGETDIR$USERFILE } function fullbackup { tar -zcvpf $TARGETDIR$OUTPUTFILE $SOURCEDIR } if [ $2 = f ]; then echo "Running Full Backup" echo "-------------------" fullbackup exit elif [ $2 = i ]; then echo "Running Incremental Backup" echo "--------------------------" incbackup exit else echo "usage ./backupscript [username] [f for full or i for incremental]" fi exit #!/bin/bash SOURCEDIR="/home/$1" TARGETDIR="/mnt/backup/" OUTPUTFILE=$1backup-$(date +%Y%m%d).tar.gz USERFILE="$1backup-.tar.gz" function incbackup { echo "Extracting Previous Backup" tar -xvfz $TARGETDIR$USERFILE echo "Updating Backup File" tar -uvfz $TARGETDIR$USERFILE } function fullbackup { tar -zcvpf $TARGETDIR$OUTPUTFILE $SOURCEDIR } if [ $2 = f ]; then echo "Running Full Backup" echo "-------------------" fullbackup exit elif [ $2 = i ]; then echo "Running Incremental Backup" echo "--------------------------" incbackup exit else echo "usage ./backupscript [username] [f for full or i for incremental]" fi exit I had done a full backup on the 8th of April and here's the output when I try to do an incremental today: carl@ubuntubox:~$ ./backupscript carl i Running Incremental Backup -------------------------- Extracting Previous Backup tar: /mnt/backup/carlbackup-20120408.tar.gz: Not found in archive tar: Exiting with failure status due to previous errors Updating Backup File tar: Removing leading `/' from member names /mnt/backup/carlbackup-20120408.tar.gz carl@ubuntubox:~$ Do I need different flags or is it just not possible to use gzip when doing this type of incremental backup?

Apr 10th, 2012, 5:18 AM	#5
sharted Hobbyist Programmer Join Date: Feb 2012 Posts: 119 Rep Power: 2	Re: BASH backup script I see several things you might benefit from considering: 1) you never check the return value of tar. You can do this by look at the $? variable; 2) I _think_ this error message might be because you have more than one backup in your /mnt/backup directory. When you pass more arguments to tar's extract capability it tries to extract subsequent files from the archive. I.e. imagine that /mnt/backup/carlbackup-*.tar.gz expands to /mnt/backup/carlbackup-20120407.tar.gz /mnt/backup/carlbackup-20120408.tar.gz tar will think you want to extract /mnt/backup/carlbackup-20120408.tar.gz from /mnt/backup/carlbackup-20120407.tar.gz. Given that this first file probably doesn't exist in the backup, you'll see the error message you see. Of course, I could be completely wrong about this.... What's in your backup directory? Have you tried doing what you want to do just at the command line? hth

Apr 10th, 2012, 5:30 AM	#6
carlw Newbie Join Date: Mar 2012 Posts: 29 Rep Power: 0	Re: BASH backup script Nice to hear from you again Sharted! You're right, it doesn't work on the command line. carl@ubuntubox:~$ cd /mnt/backup carl@ubuntubox:/mnt/backup$ ls backup-20120408.tgz carlbackup-20120408.tar.gz carl@ubuntubox:/mnt/backup$ tar -xvfz carlbackup-20120408.tar.gz tar: z: Cannot open: No such file or directory tar: Error is not recoverable: exiting now carl@ubuntubox:/mnt/backup$ tar -xvfz /mnt/backup/carlbackup-20120408.tar.gz tar: z: Cannot open: No such file or directory tar: Error is not recoverable: exiting now OH WAIT I JUST FOUND THIS -- http://stackoverflow.com/questions/7...mmand-tar-xvfz You leave the dash off the flags for some reason. Also I need sudo - so I'll lookup how to implement sudo in to the script.

Apr 25th, 2012, 8:45 AM	#7
carlw Newbie Join Date: Mar 2012 Posts: 29 Rep Power: 0	Re: BASH backup script oh no! Sharted is gone....I'll never get an answer!

Apr 25th, 2012, 9:19 AM	#8
Raybc Hobbyist Programmer Join Date: Jan 2011 Location: Australia Posts: 195 Rep Power: 3	Re: BASH backup script Where's sharted? On a well-earned holiday? I don't know much about archiving but the test command error is from the @ parameter expanding. Why not try (Toggle Plain Text) if [ "$2" = f ]; then echo "Running Full Backup" echo "-------------------" fullbackup exit elif [ "$2" = i ]; then echo "Running Incremental Backup" echo "--------------------------" incbackup exit else echo "usage ./backupscript [username] [f for full or i for incremental]" fi if [ "$2" = f ]; then echo "Running Full Backup" echo "-------------------" fullbackup exit elif [ "$2" = i ]; then echo "Running Incremental Backup" echo "--------------------------" incbackup exit else echo "usage ./backupscript [username] [f for full or i for incremental]" fi Putting quotes around the $2 returns a blank string even if $2 is not defined. You can drop the test on $1 altogether, for that part anyway. Another alternative could be to put quotes around $@, or is it $*. One will give a word, the other a list of quoted words.

Apr 25th, 2012, 9:44 AM	#9
carlw Newbie Join Date: Mar 2012 Posts: 29 Rep Power: 0	Re: BASH backup script A fellow Aussie! (I'm from Perth). Thanks for your ideas, I'll have a think about them tomorrow when I get back to testing my script. Carl

Apr 26th, 2012, 8:00 AM	#10
sharted Hobbyist Programmer Join Date: Feb 2012 Posts: 119 Rep Power: 2	Re: BASH backup script Sorry guys, I'm in the middle of moving house. Gordon Bennett, it's a lot of work! I should be done by the middle of next week.

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BASH backup script