Remote automatic backup no authe required RSA key Apache

remote_cronjob_backup.sh

#!/usr/bin/env bash

# author: cgpu

# *NOTE*:
# PLEASE FIND ATTACHED AT THE tail OF THE FILE AN APPENDIX OF
# TASKS/COMMANDS THAT WERE PERFORMED OUTSIDE OF THE .sh FILE FOR THE CRONJOB.

# STEP 0:
#___________________________________________________________________________________________________________________
#ASSIGNING DATE COMMAND IN THE REQUESTED FORMAT YYYYmmdd IN A VARIABLE
#COMMAND + SYNTAX iNFO FOUND HERE: http://bit.ly/date_in_dir_name
TODAY=`date +%Y\%m\%d`
#DESDIR
#SRCDIR


# STEP 1:
#___________________________________________________________________________________________________________________
#CREATE .tgz FILE WITH THE CONTENTS OF THE LOCAL DIR NAMED "MyFiles"
tar -zcvf /home/user14/MyFiles-"$TODAY".tgz  /home/user14/MyFiles


# STEP 2:
#___________________________________________________________________________________________________________________
#STORE SIZE OF THE .tgz FILE IN A VARIABLE, IN ORDER TO CHECK LATER IF IT "FITS" IN THE REMOTE MACHINE'S DISK SPACE
TGZSIZE=$(ls -l /home/user14/MyFiles-"$TODAY".tgz | awk '{print $5}')


# STEP 3:
#___________________________________________________________________________________________________________________
#Checksum for the created .tgz stored in a variable called LOCALSUM
#WE WILL BE LATER ON COMPARING THIS CHECKSUM WITH THE FILE'S IN THE DES DIR
#COMMAND + (parentheses) SYNTAX iNFO FOUND HERE: http://bit.ly/cmmnd_in_var
#*NOTE*:  using redirection <, because if not, the full path (instead of a dash -)
#will appear on stdout and will be stored as part of the checksum var;
#since full path obviously doesn't match for our file on remote Vs local,
#storing full path next to the checksum, would always result in mismatching LOCALSUM Vs REMOTESUM
LOCALSUM=$(sha256sum < /home/user14/MyFiles-"$TODAY".tgz)


# STEP 4:
#___________________________________________________________________________________________________________________
#BEFORE .tgz FILE TRANSFER, CHECKING DISK SPACE AVAILABILITY IN THE REMOTE MACHINE:
#df command, tailored into the following 1-liner will give us the kb of available disk space for the remote machine
# COMMAND + SYNTAX iNFO FOUND HERE: http://bit.ly/df_minus_k
# [i]: df -k
# [o]: $1:Filesystem   $2:1K-blocks  $3:Used $4:Available   5:Use%   $6:Mounted
# We will need $4
REMOTEDISK=$(ssh cgpu@111.111.111.111 -p30022 df -k /home/ | tail -1 | awk '{print $4}')


# STEP 5:
#___________________________________________________________________________________________________________________
#NOW ALL WE HAVE TO DO IS ARITHMETICALLY COMPARE THE REMOTEDISK Vs TGZSIZE kb number TO DECIDE
#IF THERE'S ADEQUATE SPACE FOR OUR .tgz FILE IN THE REMOTE MACHINE
#THE RATIONALE IS: IF WE KNOW THAT the REMOTE DISK SPACE IS INADEQUATE, WHY ATTEMPT SENDING THE FILE ANYWAY?
#INSTEAD, WE WILL BE SENDING AN EMAIL TO INFORM ABOUT THE LACK OF SPACE.
#THE LOOP GOES LIKE THIS:

#IF  : CHECK FOR ZERO SPACE IN REMOTE, aka "$REMOTEDISK" -eq 0
#ELIF: CHECK FOR INADEQUATE SPACE, aka "$REMOTEDISK" -lt "$TGZSIZE"
#ELSE: PROCEED TO TRASNFER
      #NEST ANOTHER IF TO CHECK FILE INTEGRITY IN THE DES DIR

# COMMAND + SYNTAX iNFO - Arithm.Comparison: http://bit.ly/arithm_cmparson  (-eq -gt -lt, from here as well)
# COMMAND + SYNTAX iNFO - SCP: http://bit.ly/scp_examples
# COMMAND + SYNTAX iNFO - mail: http://bit.ly/mail_minu
# COMMAND about THE bit-bucketed STDOUT : http://bit.ly/spare_me_the_stdout

#IF DISK SPACE IS OK, THEN PROCEED TO TRASFER AND EVALUATE SRC AND DES FILE CHECKSUMS.
#HENCE THE NESTED LOOP IN THE END, THAT SHOULD ONLY BE EVALUATED WHEN SCP is True.


if [ "$REMOTEDISK" -eq 0 ] #checked that it works and the email is being sent, by changing to -ne, both for if and elif
then
    mail -s "Remote Disk Full;cannot proceed with Backup" user1 < /dev/null
elif [ "$REMOTEDISK" -lt "$TGZSIZE" ]
then
    mail -s "Remote Disk Space inadequate;cannot proceed with Backup" user1 < /dev/null
else
    scp /home/user14/MyFiles-"$TODAY".tgz user14@139.91.75.10:/home/user14/Backup/  && REMOTESUM=$(ssh user14@139.91.75.10 -p30022 sha256sum <  /home/user14/Backup/MyFiles-"`date +%Y\%m\%d`".tgz) #sorry about this one line :/

    # STEP 6:
    #___________________________________________________________________________________________________________________
    #Given else, from STEP 5
    #WE NEED TO CHECK THAT THE .tgz FILE HAS BEEN TRANSFERED UNALTERED.
    #WE WILL CONNECT via ssh TO REMOTE MACHINE
    #in order to get checksum of the .tgz in the destination dir, aka Backup dir.
    #ENTER NESTED LOOP:
    if [ "$LOCALSUM" == "$REMOTESUM" ] #cannot use -eq here because checksums are not integers
    then
        mail -s "Backup successfull :)" user1 < /dev/null #this just denotes that yes, we know it's empty and we dont mind.

    else
        mail -s "Backup failed :/" user1 < /dev/null
    fi
fi


# STEP 7:
# ___________________________________________________________________________________________________________________
# After the attempt for scp, check  for scp exit code errors:
# A list with exit status codes for errors can be found here: /home/user14/scp_exit_status.txt
# which was initially found here: http://bit.ly/scp_exit_status_list


SCPEXIT=$?

if [ $SCPEXIT -eq 4 ]     #if connection to host failed
then
        mail -s "Backup failed; could not establish connection to remote machine."
elif [ $SCPEXIT -eq 74 ]       #if connection failed
then
        mail -s "Backup failed; could not establish connection to remote machine."
elif [ $SCPEXIT -eq 5 ]       #if connection broken
then
        mail -s "Backup failed; connection to remote machine was interrupted."
fi

#*NOTE*: Sample failed email messages can be found unread at user14 inbox


# ALSO, TASKS IMPLEMENTED OUTSIDE THE .sh FILE THAT WILL BE cronjob-ed:
# COMMANDS ARE DENOTED WITH 2 HASHTAGS:

# CREATE DIR AND FILES
## mkdir MyFiles Backup

## cd MyFiles | touch file_0_scWv.txt  file_1_ntHv.txt file_2_blMd.txt #then used emacs to add sth random


# GENERATE PUBLIC-PRIVATE KEY PAIR FOR LOGIN-LESS SCP #assymetric ftw :)
# COMMAND + SYNTAX iNFO - PUBLIC/PRIVATE KEY AUTH: http://bit.ly/public_private_pair

## ssh-keygen -t rsa

# left evrything blank, no passphrase, no nothing
# identification in: /home/user14/.ssh/id_rsa.
# public key: in /home/user14/.ssh/id_rsa.pub.

# THEN:
##cat .ssh/id_rsa.pub | ssh user14@Bioinfo-Grad-Server 'cat >> .ssh/authorized_keys'
# entered passwd  at this point

# SUBSEQUENTLY PROCEEDED TO SCP TRANSFER, 
# TO ALLOW PERMISSIONS FOR FUTURE TRANSFERS

# Got the following message:

# The authenticity of host '111.111.111.111 (111.111.111.111)' can't be established.
# ECDSA key fingerprint is 00:df:00:fc:00:e4:00:00:f6:00:3e:c6:8c:ab:00:00.  
# strange bc my cmmand had rsa
# Are you sure you want to continue connecting (yes/no)? yes
# Warning: Permanently added '111.111.111.111' (ECDSA) to the list of known hosts.
# MyFiles-20170215.tgz                          100% 1827KB   1.8MB/s   00:00

# Authentication established, ready for automated backups.

# ONCE .sh FILE WAS READY,
# ALSO MADE IT EXECUTABLE:
## chmod u+x user14finalex.sh
# and made sure the file is somewhere in home dir


# FINAL STEP: SETTING UP AS CRONJOB
# used readlink cmmand to get full path of the .sh file:
## [i]: readlink -f user14finalex.sh
#  [o]: /home/user14/user14finalex.sh

## crontab -e
## 55 23 * * * /bin/bash /home/user14/user14finalex.sh