bash scripting

STAN71 · 06-11-2014, 12:17 AM

hello guys!
I'm newbie in linux bash scripting. Recently taking class Unix/Linux OS's where our instructor started from bash scripting. On the week 2 we already had to learn loops, that just to show how fast he was going through the course. And of course, majority of students got no clue what they do, including present party. I have to finish my last assignment on bash scripting, all class copied scripts letter by letter from the "board" when our instructor was running scripts for this particular assignment, but it doesn't work

.
Would you please take a look at the scripts and tell me what is wrong and what needs to be changed?
The goal of this script is to display user's directories and files in those directories.But instead, that gives me directories of the whole system, all it's files and then at the end of it display users.
Thank you in advance.
Stokil.
Here is my code:
#!/bin/bash
# Name: userreport
# By: Stokil
# Date: 6/4/2014
# Purpose: report of all users on system
########################################
clear
x=500
while [ $x -lt 510 ]
do
user=`grep ":x:$x:" /etc/passwd | cut -f1 -d:`

echo "#####################################"
echo "$user"
echo "#####################################"
echo " "

echo "Home Directory"
ls -ld `grep "$user" /etc/passwd | cut -f6 -d":"`
echo " "
echo "Estimate Directory Size"
echo "======================="
du -h -s /home/$user | cut -f6 -d":" | cut -f1 -d"/"
echo " "
echo "Display the User information"
echo "============================"
grep "$user" /etc/passwd
echo " "
echo "Shadow file"
echo "==========="
grep "$user" /etc/shadow | cut -f2 -d":"
echo " "
echo "Groups"
echo "======"
grep "$user" /etc/group | cut -f1 -d":"
echo " "
echo "Last Login"
echo "===="
last $user
echo "ls"
tree -d `grep "$user" /etc/passwd |cut -f6 -d":"`

echo "============================"
echo " "
let x=$x+1
done

pan64 · 06-11-2014, 01:31 AM

1. instead of grep "$user" /etc/passwd | cut .... you can write: awk -F: '/'$user'/ { print $1 }' /etc/passwd # replace $1 to $2, $3, $NF, whatever you need
2. you grep the home dir from /etc/passwd but later you use /home/$user (instead of the collected data)
3. use variable to store home dir
4. group info can be retrieved by the command groups <userid>

use [code]here comes your script[/code] to keep formatting

STAN71 · 06-11-2014, 02:01 AM

Quote:

Originally Posted by pan64

1. instead of grep "$user" /etc/passwd | cut .... you can write: awk -F: '/'$user'/ { print $1 }' /etc/passwd # replace $1 to $2, $3, $NF, whatever you need
2. you grep the home dir from /etc/passwd but later you use /home/$user (instead of the collected data)
3. use variable to store home dir
4. group info can be retrieved by the command groups <userid>

use [code]here comes your script[/code] to keep formatting

I'm really sorry for the stupid question, but should i do awk command even after while "do"? Or that has to stay as grep?
I like Linux and that was the main reason for taking that class, but here is a link on reviews and average grades people get in this class. You ether has to be a linux gig already or you got nothing

https://www.myedu.com/MHCC-Mt-Hood-C...ourse/2313014/
Thank you for reply

pan64 · 06-11-2014, 02:14 AM

I do not really care about that class, and you can reach any level (of knowledge) - if you want to do so. So there is no stupid question, just ask and learn and practice and you will win.

If you are not really familiar with shell scripting and awk I suggest you to do only small steps, little modifications. For example try this line: grep "$user" /etc/shadow | cut -f2 -d":" and replace only this with an awk script.

see man pages also (for example man awk or man bash), or:
http://www.tldp.org/LDP/abs/html/

STAN71 · 06-11-2014, 02:22 AM

Quote:

Originally Posted by pan64

I do not really care about that class, and you can reach any level (of knowledge) - if you want to do so. So there is no stupid question, just ask and learn and practice and you will win.

If you are not really familiar with shell scripting and awk I suggest you to do only small steps, little modifications. For example try this line: grep "$user" /etc/shadow | cut -f2 -d":" and replace only this with an awk script.

see man pages also (for example man awk or man bash), or:
http://www.tldp.org/LDP/abs/html/

thank you,
I did replace some of the grep commands for awk, but it still gives me a tons of info i don't need
here is some of the very bottom of the script:
| `-- usage
`-- yp
`-- binding
/var/lib/avahi-autoipd [error opening dir]
/var/gdm
/home/sabayon [error opening dir]
/home/stanislav
`-- Desktop
/home/mikeb
/home/gregb
|-- home
`-- school
|-- arithmetic
|-- reading
`-- writing
/home/peterb
|-- home
`-- school
|-- arithmetic
|-- reading
`-- writing
/home/bobbyb
|-- home
`-- school
|-- arithmetic
|-- reading
`-- writing
/home/marshab
|-- home
`-- school
|-- arithmetic
|-- reading
`-- writing
/home/janb
|-- home
`-- school
|-- arithmetic
|-- reading
`-- writing
/home/cindyb
|-- home
`-- school
|-- arithmetic
|-- reading
`-- writing
/home/carolb
|-- home
`-- school
|-- arithmetic
|-- reading
`-- writing

107309 directories
as you can see the users start at /home/stanislav and below. But the stuff above it, that is what i do not need. It is in /etc/passwd directory, but how to get rid of it?
I'm ready to learn.

Thank you very much Mr. Pan64 for your help. I'll try to mess with it a little more tomorrow. And also appreciate for useful link.

Have a good DAY.

pan64 · 06-11-2014, 02:46 AM

there was something wrong at the beginning I do not understand.
You may try to skip unwanted users
also you can insert set -xv at the beginning and you will see how that script works

STAN71 · 06-11-2014, 02:52 AM

Quote:

Originally Posted by pan64

there was something wrong at the beginning I do not understand.
You may try to skip unwanted users
also you can insert set -xv at the beginning and you will see how that script works

pan64 · 06-11-2014, 03:33 AM

you need to insert the line set -xv at the beginning of the script:
#!/bin/bash
set -xv
.....

and when you run it you will see a lot of information about the execution. Just check it line by line to understand what's happening.
set -xv will not influence/modify the execution itself just print a lot of information about that.

Try this instead of that while loop:

Code:

for u in `awk -F: '{print $3}' /etc/passwd`;
do
# skip user
   [[ $u -eq 0 ]] && continue
  # your code
done

fotoguy · 06-11-2014, 03:48 PM

I know i'm not answering your post buy this is a link to a beginners guide to bash scripting that will help give you a good understanding of bash scripting, not sure if your teacher has given you something like this already, I myself have the advanced bash scripting tuttorial pdf printed for me which I use for referencing all the time, even after 14 years of using linux.

http://www.tldp.org/LDP/Bash-Beginne...ners-Guide.pdf

Hope this helps

STAN71 · 06-11-2014, 07:53 PM

Quote:

Originally Posted by fotoguy

I know i'm not answering your post buy this is a link to a beginners guide to bash scripting that will help give you a good understanding of bash scripting, not sure if your teacher has given you something like this already, I myself have the advanced bash scripting tuttorial pdf printed for me which I use for referencing all the time, even after 14 years of using linux.

http://www.tldp.org/LDP/Bash-Beginne...ners-Guide.pdf

Hope this helps

No, my instructor didn't give us anything about bash scripting. It suppose to be a linux server class.
Thank you very much for this link.

STAN71 · 06-12-2014, 02:19 AM

Quote:

Originally Posted by pan64

you need to insert the line set -xv at the beginning of the script:
#!/bin/bash
set -xv
.....

and when you run it you will see a lot of information about the execution. Just check it line by line to understand what's happening.
set -xv will not influence/modify the execution itself just print a lot of information about that.

Try this instead of that while loop:

Code:

for u in `awk -F: '{print $3}' /etc/passwd`;
do
# skip user
   [[ $u -eq 0 ]] && continue
  # your code
done

Thank you for your help. I finally found solution for the problem i had with this script. There was users numbers not in sequence.
Here what i added to the script to solve this problem:
x=500
while [ $x -lt 509 ]
do
user=`grep ":x:$x:" /etc/passwd | cut -f1 -d":"`

let x=$x+1

if [[ $user == "" ]]; then
#echo "group_id=$x not found in /etc/passwd";
continue;
fi
The rest of the script I left same as it was except let x=$x+1
Because I place it at the beginning.
Now it works like a charm.