Ok I am a PC/Network technician at a local energy company, the how or why isn't really important, but I am a linux amatuer and I need to know what these scripts mean.
Code:
1. #!/bin/bash
2. #
3. date
4. echo 'Would you like to execute the command (y/n)? \c'
5. read ANSWER
6. if [ $ANSWER = "y" -o $ANSWER = "Y" ]
7. then
8. find /media/backup -name '*.tar.gz' -type f -daystart -ctime +7 -exec rm -f {} \;
9. else
10. find /media/backup -name '*.tar.gz' -type f -daystart -ctime +7 -print
11. fi
Code:
1. #!/bin/bash
2. #
3. date
4. case "$1" in
5. start)
6. echo '-- executing command in start section --'
7. SERVSTAT=`service httpd status | grep running`
8. if [ ${#SERVSTAT} -eq 0 ]
9. then
10. service httpd start
11. else
12. echo 'service already running'
13. fi
14. ;;
15. stop)
16. echo '-- executing command in stop section --'
17. SERVSTAT=`service httpd status | grep stopped`
18. if [ ${#SERVSTAT} -eq 0 ]
19. then
20. service httpd stop
21. else
22. echo 'service already stopped'
23. fi
24. ;;
25. restart)
26. echo '-- executing command in restart section --'
27. service httpd restart
28. ;;
29. esac
If someone could explain these two scripts to me in a detailed manner, line by line detail would be nice. This will help me immensely in my job, thanks!
Last edited by methyl; 02-28-2012 at 09:27 AM..
Reason: remove microfont, add code tags
#!/bin/bash
# the previous line indicates the shell that should interpret the script
#
date # print the current date/time to the tty
echo 'Would you like to execute the command (y/n)? \c' # prompt user \c keeps the cursor on the same line
read ANSWER # read response from keyboard; assign to variable ANSWER
if [ $ANSWER = "y" -o $ANSWER = "Y" ] # test user's answer if Y or y execute the first find
then
# this find command searches the directory /mdeia/backup, and all subdirectories, for any
# tiles named *.targ.gz and were last modified more than 7 days ago. For each file it
# finds, it removes the file.
find /media/backup -name '*.tar.gz' -type f -daystart -ctime +7 -exec rm -f {} \;
else
# this find command (executed if user does not type y) finds the same files, but
# just prints the list on the terminal -- a previvew of what would have been deleted
# if the user typed y to the prompt.
find /media/backup -name '*.tar.gz' -type f -daystart -ctime +7 -print
fi
---------- Post updated at 22:40 ---------- Previous update was at 22:32 ----------
Explanation of the second script
Code:
#!/bin/bash
#
date
case "$1" in # examine the first parameter passed to the script
# it is expected to be start, stop or restart
start) # execute the following code when $1 is start
echo '-- executing command in start section --'
SERVSTAT=`service httpd status | grep running` # execute the command service, pick out lines with running and assign to a variable
if [ ${#SERVSTAT} -eq 0 ] # if the length of the contents of SERVSTAT are zero (nothing found by command)
then
service httpd start # start the service
else
echo 'service already running' # just write that the service is already running
fi
;; # end of code block, skip to esac
stop) # execute this code block when $1 is stop
echo '-- executing command in stop section --'
SERVSTAT=`service httpd status | grep stopped` # execute the service command and search for the word stopped
if [ ${#SERVSTAT} -eq 0 ]
then
service httpd stop # if the command did not find stopped service, then stop it
else
echo 'service already stopped' # else just echo state to the user
fi
;; # end of code block, skip to esac
restart)
echo '-- executing command in restart section --'
service httpd restart # execute the restart command
;; # end of code block, skip to esac
esac
Hope this helps.
Last edited by jim mcnamara; 02-28-2012 at 12:00 PM..
Just a tip, become familiar with the "man" command, which shows you the manual page for a command i.e :
Code:
$ man date
to learn about the date command and its options. Of course these days you can ask the google too. When I was learning I did what you are doing, taking an existing script and studying it line by line, doing a man and reading about each command I was not familiar with. When you learn what it does, add a comment above or to the right of it, like what agama did for you. Keep a copy of your edited script in your own directory for reference. Pretty soon it will start clicking. Then you need to learn the vi editor!
Perusing posts here will be a help too, use the search functionality for a specific question. Believe me, whatever question you have, you will not be the first to ask it. Use a meaningful subject line for your post, you'll get more views and replies, plus future searchers will have a better chance at finding information.
People here are real helpful, but mention the system and shell you are using too when asking a question, it matters. Be thankful there is a resource like this site. Back in the day when I asked a question, the response was usually a gruff "RTFM!"! lol
