Script that mount LVM

Danielb630 · 03-15-2021, 02:15 PM

hey guys, im trying to write a script that gets a .csv file and creates lvm's and mount points , mount the lvm to the mount points and writing into /etc/fstab,
but it seems that the for loop isnt working for me and it prints insted of creating my
variables , can someone give it a look and tell me where are my mistakes?

the .csv file

Code:

ProductsLV, /products
OracleLV, /products/Oracle
PlsqlLV, /products/plsql

my script:

Code:

#!/bin/bash


for i in 'cat list.csv'
do
    lv_name1='echo $i | cut -d, -f1 | sed '1!d''
    lv_name2='echo $i | cut -d, -f1 | sed '2!d''
    lv_name3='echo $i | cut -d, -f1 | sed '3!d''
    mount_point1='echo $i | cut -d, -f2 | cut -c 2- | sed '1!d''
    mount_point2='echo $i | cut -d, -f2 | cut -c 2- | sed '2!d''
    mount_point3='echo $i | cut -d, -f2 | cut -c 2- | sed '3!d''
    vg_name='centos'
        
        lvcreate -L 10m -n $lv_name1 $vg_name
	lvcreate -L 10m -n $lv_name2 $vg_name
	lvcreate -L 10m -n $lv_name3 $vg_name
	
	mkdir -p $mount_point1
	mkdir -p $mount_point2
	mkdir -p $mount_point3
	
	mount -t ext4 /dev/$vg_name/$lv_name1 $mount_point1
	mount -t ext4 /dev/$vg_name/$lv_name2 $mount_point2
	mount -t ext4 /dev/$vg_name/$lv_name3 $mount_point3
	mount -a
	
	echo "/dev/$vg_name/$lv_name1 $mount_point1 ext4 defaults 0 0">>/etc/fstab
	echo "/dev/$vg_name/$lv_name2 $mount_point2 ext4 defaults 0 0">>/etc/fstab
	echo "/dev/$vg_name/$lv_name3 $mount_point3 ext4 defaults 0 0">>/etc/fstab
done

michaelk · 03-15-2021, 08:27 PM

Welcome to LinuxQuestions.

You need to understand loops and how reading lines from a file works.

https://www.cyberciti.biz/faq/unix-h...ine-from-file/

Is this homework?

computersavvy · 03-15-2021, 09:41 PM

First, as has been said you need to understand reading from a file and loops.

In your script you use the same line read and process it 3 different times, creating 3 different LVs with each.

Since you read one line, process that one line each time through the loop. The second time through the loop you process the second line, etc.

You also need to understand how LVM names and accesses LVs.
Although it is possible to mount things like you did, the standard way of referencing an LV for mounting is like any other partition.
"mount /dev/mapper/$vgname-$lvname /mount/point"
Why are you creating an lv for what appears to be a simple mount point for the second and 3rd LVs? Will it also contain data or is it a simple mount point?

After the LV is created it needs to be formatted with a file system before mounting.
"mkfs.ext4 /dev/mapper/$vgname-$lvname"
After the first LV is created and mounted, before you create the mount point for the second and subsequent LVs (inside it) you should make certain the first is actually mounted so the rest of the structure creation is done properly

The processes you are performing requires that this script be executed with root (sudo) privledges.

CSV files use "," for separators; not ", " (comma-space)
cut does quite nicely for taking part of a line. No need for multiple cuts or sed on those simple lines.

berndbausch · 03-16-2021, 12:27 AM

One mistake is illustrated by this line:

Code:

for i in 'cat list.csv'

Your intention was to use backquotes instead of normal quote characters. Hard to see the mistake, since they look so similar. Better use $(cat list.csv). You make the same mistake repeatedly in the loop body.

Next, the for loop doesn't assign entire lines to $i, but words. For this reason, your echo | cut pipelines won't work.

Finally, you create logical volumes, but you don't format them as filesystems. Thus, they can't be mounted.

And I don't understand what the sed commands are for.

pan64 · 03-16-2021, 03:10 AM

additionally you might want to try shellcheck.

Code:

$ shellcheck myscript
 
Line 4:
for i in 'cat list.csv'
^-- SC2034: i appears unused. Verify use (or export if used externally).
         ^-- SC2041: This is a literal string. To run as a command, use $(..) instead of '..' .