Linux World

Resolve DNS name in ubuntu

2026-02-15T01:41:00.000-08:00

Enabling Active Directory DNS Resolution on Ubuntu

Problem Statement: An Ubuntu VM needs to communicate with several Windows VMs that are members of an Active Directory (AD) domain. While the Windows machines can resolve each other's hostnames via the Domain Controller, the Ubuntu VM fails to resolve these DNS names, preventing seamless connectivity.

Objective: Configure the Ubuntu VM to use the Active Directory Domain Controller (DC) as its primary DNS server for name resolution.

Technical Solution: Updating the Nameserver

To allow Ubuntu to "see" the AD environment, you must point its DNS configuration to the IP address of the Domain Controller.

1. Identify the DNS IP

On any of your Windows VMs already in the domain, find the DNS server IP (usually the IP of your Domain Controller).

2. Update the Configuration

In Linux, DNS resolution is primarily handled by the resolv.conf file. You need to add your AD DNS IP to this file.

File Path: /etc/resolv.conf
Action: Add a nameserver entry at the top of the file.

Example Entry

nameserver 192.168.1.10  # Replace with your AD DNS IP
search yourdomain.local  # Optional: allows resolution of short names

Modern Ubuntu versions (18.04 and later) use a service called systemd-resolved. If you manually edit /etc/resolv.conf, your changes might be overwritten after a reboot.

For a permanent fix, it is usually better to:

Edit the Netplan configuration in /etc/netplan/.
Or, use systemd-resolved by linking the file:
ln -sf /run/systemd/resolve/stub-resolv.conf /etc/resolv.conf
Note: If you are in a production environment, ensure that your AD DNS server is also configured to "Forward" requests to a public DNS (like 8.8.8.8) so your Ubuntu VM doesn't lose general internet access while searching for the domain.

Specific Netplan commands to make this DNS change permanent

IF you're working with a modern version of Ubuntu (like 20.04, 22.04, or 24.04), using Netplan is the most reliable way to ensure your DNS settings survive a reboot.

Here is how to apply the fix permanently:

1. Locate your Netplan Configuration

Netplan configuration files are YAML files located in /etc/netplan/. Run this command to find the filename:

ls /etc/netplan/

(Common filenames are 01-netcfg.yaml, 50-cloud-init.yaml, or 00-installer-config.yaml.)

2. Edit the File

Open the file with root privileges (replace filename.yaml with your actual file name):

sudo nano /etc/netplan/filename.yaml

3. Add the DNS/Nameserver Info

Update the nameservers section under your network interface (usually eth0 or ens33). It should look like this:

YAML
network:
  version: 2
  ethernets:
    eth0:
      dhcp4: true
      nameservers:
        addresses: [192.168.1.10, 8.8.8.8] # Your AD DNS IP first, then a backup
        search: [yourdomain.local]         # Your AD Domain name

4. Apply the Changes

Save the file (Ctrl+O, Enter) and exit (Ctrl+X). Then, run:

sudo netplan apply

How to Verify the Fix

Once applied, you can check if Ubuntu is actually talking to your Active Directory DNS by running:

resolvectl status

Look for the "DNS Servers" section under your active interface to confirm your AD IP is listed.

Black screen in vsphere 7.x client on installing unbuntu

2023-10-15T01:53:00.000-07:00

On booting an Installation of ubuntu on the vspehere 7.x client can sometimes show a black screen instead of the actual GUI of ubunutu. One the possible reasons for this could be a simple setting in the virtual machine. To check if its problem with vm setting try the following.

Power off vm and go to edit settings-> virtual hardware->video card and select option "auto detect settings" and un-check box enable 3D support if checked.

Once the setting is changed, power on the virtual machine and you should be able to see the ubuntu gui.

Resize Images Using GIMP

2022-08-23T04:31:00.000-07:00

Here is quick look at the steps that can be followed to resize an Image using gimp. Resize could be either to reduce the height and width or the memory size of the image. For example if you need the a image to be of only 40KB, and the current size is 100KB then you can resize the image to a smaller height and width and reduce the memory size of the image .

vmware vmplayer unable to install all modules ubuntu

2022-07-20T04:20:00.003-07:00

While installing the vmplayer 16.1.2 in ubuntu 20.04 the installation failed with the error message

The logs indicated that the issue with the installation of the module vmmon. One of the workaround that worked was to download the source file from

After downloading, unzip the files and go to the folder vmmon-only/include . Open the file vm_asm_x86.h and comment out a part of the code a shown in the figure below.

Now rebuild the new modules and install using the follwing set of commands, running them inside the new folder that was downloaded from the above link.

Now launch the vmplayer, it should open with out any errors. Please note that the solution has been verified on the specific version mentioned so it might or might not work on all versions.

Linux bash script to find Average of prime numbers in range

2022-07-19T21:55:00.000-07:00

This post in reponse to a comment on the post " Linux script to find prime numbers in a range of numbers " The request was to find the average of all the prime numbers found in the given range.

Save the file say as average_prime_range.sh Execute it using bash.

Following is a sample output

Sending mails from the command line to multiple receipents using gnome-gmail.

2022-04-24T06:06:00.001-07:00

Here is a script which can be used to send a common mail to all number of receipients, with all the recepient mail ids stored in a text file.

The script uses the tool gnome-gmail, which can be installed from your package repository, In debian based systems it can be installed using

Create a file called mialIds which will have a a list of mail ids to which mails need to be sent. For example

Create a file with the following script and name it as mailscript.sh

The input variable in the script should point to the file containing the mail ids.. If the script and the file containing mail ids are in the same folder, then just the name is enough.

The variable subj is used to store the content to be filled in the subject line of the mail. The variable bod will contain the text for the body of the email.

Execute the script

If you execute it the first time, gnome-gmail will prompt you to enter the gmail id that needs to be use dfor sending the email. If the gmail is in the logged in state in the browser, it will be able to send the mail automatically, else it might open the login prompt for you to login into the gmail account. Gnome-gmail Its a great way to automate sending default emails.

[: -eq: unary operator expected

2022-04-02T22:32:00.001-07:00

The above error might come when we are using conditional operators to compare two values in a bash script. For example , conisder the following script to compare a user input number with a constant.

The above script when executed will throw the error as listed before. The error in the program is use of $ while taking the input, that is the right way of using the read command is "read without a $ symbol before the name.

The second possible reason for the error could be not passing two values to compare for the operataor , for example the script below will also throw the same error as the operator "eq" has been given only a single operand.

In the above example, we have missed passing the constant after the comparision opertaor.

Looking in the above two possibilities should fix the error.

Guess the number game in shell script

2022-03-21T03:17:00.003-07:00

Execute the following script to play "Guess the number" Game on the linux terminal. The computer picks a random number between 0 and 10 and the user has to guess the same, with in 3 attempts.

Save the file as "guessTheNumber.sh" and execute the script from the terminal.

The output would look as shown below. You can increase the number of attempts by changing the value of the attempts variable .

Script to create 2022 on linux terminal with a mask on the 0.

2021-12-30T21:21:00.000-08:00

Here is a script you can run on the linux terminal to generate 2022 on the terminal using any charachter you want. With the charachter 0 covered partiall to indicate the need for mask in the new year too.

#!/bin/bash

#create 2022 on terminal using any user specified character
str_dwn() {
rows=$1
s_start=$2
char=$4
str_st_row=$3
rows_end=$((str_st_row+rows))
for((i=str_st_row;i<rows_end;i++))
do 
tput cup $i $s_start
printf "$char " 
done
echo""
}

backslash() {
b_st_row=$1
b_st_cols=$2
b_char=$3
b_r_end=$((b_st_row + 5 ))
for((p=b_st_row;p<b_r_end;p++))
do 
tput setaf $4
tput cup $p $b_st_cols
printf "$b_char " 
((b_st_cols++))
done
echo""
}

forward() {
f_st_row=$1
f_st_cols=$2
f_len=$3
f_char=$4

f_r_end=$((f_st_row + $f_len))

for((i=f_st_row;i<f_r_end;i++))
do 
tput cup $i $f_st_cols
printf "$f_char "
 ((f_st_cols--))
done
echo""

}

horizontal() {
hrow=$2
hstart=$1
hcols=$3
char=$4

end=$((hstart + hcols))

for((i=hstart;i<=end;i++))
do 
tput cup $hrow $i
printf "$char" 
done
echo""
}

half_horizontal() {
hrow=$2
hstart=$1
hcols=$(($3/2))
char=$4

end=$((hstart + hcols))

for((i=hstart;i<=end;i++))
do 
tput cup $hrow $i
printf "$char" 
done
echo""
}

gen_rand() {
num1=$1

if [ $num1 -eq 0 ]
then
temp=$(($RANDOM % 2))
rand=$((temp + 2))

else

temp=$(($RANDOM % 5))
rand=$((temp + num1))
fi
}

two() {

hstart_2=$1
hrow_be=$2
hcols_2=$3
char=$4
color=$5

set_color

horizontal $hstart_2 $hrow_be $hcols_2 "$char"

st_row_2=$((hrow_be+1))
f_st_cols_2=$((hstart_2+hcols_2))

forward $st_row_2 $f_st_cols_2 5 "$char" $color
hstart_2_lo=$start
hrow_2_lo=$((hrow_be+6))
hcols_2_lo=5
horizontal $hstart_2_lo $hrow_2_lo $hcols_2_lo "$char"

}

zero() {

set_color

hstart_0=$((f_st_cols_2 +4))
hcols_0=5
horizontal $hstart_0 $hrow_be $hcols_0 "$char"

str_dwn_col_0=$hstart_0
str_dwn_row_0=$((hrow_be + 1))
str_dwn 6 $str_dwn_col_0 $str_dwn_row_0 "$char"

hstart_0_lo=$((f_st_cols_2 +4))
hcols_0_lo=6
hrow_0_lo=$((hrow_be+4))
horizontal $hstart_0 $hrow_0_lo $hcols_0 "$char"

hrow_0_lo=$((hrow_be+5))
horizontal $hstart_0 $hrow_0_lo $hcols_0 "$char"

hrow_0_lo=$((hrow_be+6))
horizontal $hstart_0 $hrow_0_lo $hcols_0 "$char"

str_dwn_col_rig_0=$((hstart_0 +5))
str_dwn_row_rig_0=$((hrow_be + 1))
str_dwn 6 $str_dwn_col_rig_0 $str_dwn_row_rig_0 "$char"
}

twoo() {
set_color

set_color

##############################
hstart_2=$((str_dwn_col_rig_0 +2))
hcols_2=6
horizontal $hstart_2 $hrow_be $hcols_2 "$char" 
###############################################
st_row_2=$((hrow_be+1))
f_st_cols_2=$((hstart_2+hcols_2))

forward $st_row_2 $f_st_cols_2 5 "$char" $color
######################################################
hstart_2_lo=$hstart_2
hrow_2_lo=$((hrow_be+6))
hcols_2_lo=5
horizontal $hstart_2_lo $hrow_2_lo $hcols_2_lo "$char" 
}

twooo() {
set_color

set_color

##############################
hstart_2=$((str_dwn_col_rig_0 +10))
hcols_2=6
horizontal $hstart_2 $hrow_be $hcols_2 "$char" 
###############################################
st_row_2=$((hrow_be+1))
f_st_cols_2=$((hstart_2+hcols_2))

set_color(){
color=$RANDOM 
color=$((color%6))
tput setaf $color
}

cols=`tput cols`
mid=$((cols/2))
start=$((mid-16))
#char="="
echo "What character do you want to use"
read char

tput clear
rows=5

begin_row=2
num_cols=6

two $start $begin_row $num_cols "$char" $color;zero;twoo;twooo

tput setaf 7
tput cup 9 0

save the above script say as 2022.sh and execute it on the terminal using

2022 should appear on the terminal in random colors as shown in the figure below. Note the partial shading of the charachter 0 to indicate the mask.

Script to create 2022 On Linux Terminal

2021-12-30T21:16:00.000-08:00

Here is a script you can run on the linux terminal to generate 2022 on the terminal using any charachter you want.

#!/bin/bash

backslash() {
b_st_row=$1
b_st_cols=$2
b_char=$3
b_r_end=$((b_st_row + 5 ))
for((p=b_st_row;p<b_r_end;p++))
do 
tput setaf $4
tput cup $p $b_st_cols
printf "$b_char " 
((b_st_cols++))
done
echo""
}

forward() {
f_st_row=$1
f_st_cols=$2
f_len=$3
f_char=$4

f_r_end=$((f_st_row + $f_len))

for((i=f_st_row;i<f_r_end;i++))
do 
tput cup $i $f_st_cols
printf "$f_char "
 ((f_st_cols--))
done
echo""

}

horizontal() {
hrow=$2
hstart=$1
hcols=$3
char=$4

end=$((hstart + hcols))

for((i=hstart;i<=end;i++))
do 
tput cup $hrow $i
printf "$char" 
done
echo""
}

half_horizontal() {
hrow=$2
hstart=$1
hcols=$(($3/2))
char=$4

end=$((hstart + hcols))

for((i=hstart;i<=end;i++))
do 
tput cup $hrow $i
printf "$char" 
done
echo""
}

gen_rand() {
num1=$1

if [ $num1 -eq 0 ]
then
temp=$(($RANDOM % 2))
rand=$((temp + 2))

else

temp=$(($RANDOM % 5))
rand=$((temp + num1))
fi
}

two() {

hstart_2=$1
hrow_be=$2
hcols_2=$3
char=$4
color=$5

set_color

horizontal $hstart_2 $hrow_be $hcols_2 "$char"

st_row_2=$((hrow_be+1))
f_st_cols_2=$((hstart_2+hcols_2))

forward $st_row_2 $f_st_cols_2 5 "$char" $color
hstart_2_lo=$start
hrow_2_lo=$((hrow_be+6))
hcols_2_lo=5
horizontal $hstart_2_lo $hrow_2_lo $hcols_2_lo "$char"

}

zero() {

set_color

hstart_0=$((f_st_cols_2 +4))
hcols_0=5
horizontal $hstart_0 $hrow_be $hcols_0 "$char"

str_dwn_col_0=$hstart_0
str_dwn_row_0=$((hrow_be + 1))
str_dwn 6 $str_dwn_col_0 $str_dwn_row_0 "$char"

hrow_0_lo=$((hrow_be+6))
horizontal $hstart_0 $hrow_0_lo $hcols_0 "$char"

str_dwn_col_rig_0=$((hstart_0 +5))
str_dwn_row_rig_0=$((hrow_be + 1))
str_dwn 6 $str_dwn_col_rig_0 $str_dwn_row_rig_0 "$char"
}

twoo() {
set_color

set_color

twooo() {
set_color

set_color

set_color(){
color=$RANDOM 
color=$((color%6))
tput setaf $color
}

cols=`tput cols`
mid=$((cols/2))
start=$((mid-16))

echo "What character do you want to use"
read char

tput clear
rows=5

begin_row=2
num_cols=6

two $start $begin_row $num_cols "$char" $color;zero;twoo;twooo

tput setaf 7
tput cup 9 0

save the above script say as 2022.sh and execute it on the terminal using

2022 should appear on the terminal in random colors as shown in the figure below.

div function in C to find the quotient and reminder

2021-10-18T20:05:00.000-07:00

While performin the division operation in a C program, we can get the reminted of division using the modulus operator. But getting quotient when the numbers are not completely divisble , for example if we divide 15 by 4, and want to find the quotient the usual divide operator will not be useful as it will give a floating point result. We can use the div function for this which is a part of the stdlib library. The div function takes two arguments, first one being the divident, the second one being the divisor.

The return value of the div fundtion is a structure of the form div_t, which has two member variables , Quotient and reminder.Thus to get the quotient and reminder we just ned to access these member variables in the return value of div.

Here is a example program.

bash script to generate fibonacci series

2021-10-15T11:03:00.000-07:00

Here is a linux bash script to generate fibonacci series .Fibonacci series is a sequence of numbers where each number is generated by addition of the previous two numbers in the sequence.

The script asks the user to provide how many numbers of the series have to be generated and prints out the numbers in the fibonacci series as many requested by the user.

Save the script as fibonacci,sh , open the terminal and run the script using

A look into the /dev/null driver

2021-09-11T12:32:00.004-07:00

We must have used the /dev/null to send the unwanted output from the terminal , its like a sinkhole into which we can dump any data and it is lost forever. We can only write into it but never read out of the /dev/null. For example

The string goes into the /dev/null , but does not get saved in it. If /dev/null is read, it will print nothing.

Let us look under the null device and see how this is achivedin the kernel. The null device is a charachater device, which can be noticed by listing it

The first charahcter is "c" which indicates it is a charachter device. Being a charachter driver it should have a read operation and writer file operations mapped to it. These can be found in the file mem.c . The write_null and read_null functions meant to read and write from the null device are written in the file mem.c . Let us look at the write_null

As can be seen the function does not store any data, but just returns a count of data recevied. Thus any data written into the devices does not get stored in any location and is just lost completely.

Similarly if we look at the read_null function.

We can see that the above function will always return a 0, every time is read and does not really return any data to the user space. Thus reading out of the null driver never produces any output, but the read operation succeeds everytime.

EOL while scanning string literal

2021-08-31T12:15:00.001-07:00

The following error might come in python when working with strings that have a "\" in it.

This error is generally because of the use of the backslash in a string operation. For example , consider the string

If we want to split the string using "\" as the seperator, we can not use

The above split command will throw the EOL error. To get around this, we need the escape the special meaning of the "\" by using another "\" preceding it.

Using split function by prefixing a "\" with another "\" will ensure that we do not get the EOL error

VMplayer : make: *** [Makefile:117: vmnet.ko] Error 2 Unable to install all modules. See log for details.

2021-08-17T23:16:00.002-07:00

A recent update on VMplayer16 version attempted to install the module for vmnet but it was unable to do so broke the vmplayer, with the error message

The log showed an error indicating some issue with the compilation of the vmnet module and was not able to generate the module for it.

The issue was in the vmplayer version 16.0, the simplest workaround for this is to download the vmplayer 16.1.2 from the site or any newer version avaialble and install the same. This issue has been fixed in the newer versions, and the vmplayer is able to lauch successfully.

Generate Indian Flag on the Linux Terminal

2021-08-13T12:19:00.000-07:00

Here is a script to generate something close to India Flag on the linux Terminal. The output looks as shown in he figure below .

Save the file as the flag.sh and run it in the terminal, with terminal in the full screen.

Record Sound or Voice in Ubuntu

2021-08-11T09:02:00.000-07:00

To record sound using linux/ubuntu we don't need and special softwares, a simple command line tool is available called arecord. One of the simple way to use the command in the terminal as follows.

The recording is continued as long as Cntrl+C is not pressed, recording infinitely. The recording will get saved in the file named filename.wav

If the recording needs to be stopped after a specific interval we can use the option -d

Loading modules automatically on boot

2021-04-17T20:06:00.000-07:00

Linux kernel loads all the needed modules while booting, but some modules compiled and added later or externally might need to the loaded manually at every boot. Loading of such modules can be automated using the .conf file in /etc/modules-load.d . For example we have a file named cpu-filters.conf in the modules-load.d folder.

If we look at the modules loaded in the kernel, we can see all these three modules as shown in the figure below

Now if we comment out the lp module.

Restart the computer after commenting the lp module and search for the lp module.

It can be seen the lp is not loaded this time.

Script to find if a number is odd or even using the command factor.

2021-03-27T05:41:00.002-07:00

Here is linux shell script which will find if a number is even or odd using the command factor.

Save the script as oddEven.sh and execute it using bash.

The factor command basically lists all the factors of the number, and by using grep we search for 2 using the option -c to count if 2 is present count will be 1 , else it will be 0.

Create screenshot using gimp

2021-02-12T09:39:00.002-08:00

Gimp can be used to take screenshots of the screen, or specific window or regions.

Click on File->Create->Screenshot

It will pop the following menu. providing the options to either take the screenshot of the active window, or the entire screen or a specific region. It also allows to add delay in seconds to allow us the close the gimp window and open the window of which we want to take the screenshot of.

When we select the option of screenshot of a specific region, it allows us to specify delay after which we want to select the region to be taken screenshot of and also delay in seconds after which the screenshot should be taken. So it allows us to get out of the gimp window and make the selection of the area, as well as open another application if screenshot needs to be taken of another application.

Gimp Hide all dockable windows.

2021-02-03T10:56:00.000-08:00

While working with gimp, if you want to hide all the dockable toolboxes around it, so that you can concetrate only on the image in the window, we can click on the options windows->Hide Docks as shwown

With all dockable windows hidden we are left with only the image.

Llinux Shell Script to check if a file exists

2021-01-02T21:46:00.003-08:00

Here a linux shell script which can be used to find if a file exists or not at a given location.

Save the file as checkifFileExist.sh and execute it as shown below.

When prompted enter the file name if you want to check in the current directory or enter the full path to where the presence of the file has to be checked, and the script will show if the file exists or not .

We can use the following script if we want to pass the file name to be searched for as a command line argument.

Save the file as checkifFileExist.sh and execute it as shown below.

2021 on Linux Terminal

2020-12-27T09:51:00.001-08:00

Here is a bash script which can be used to create the text 2021 on the terminal using any characher of your choice.

#!/bin/bash

#create 2021 on terminal using any user specified character
str_dwn() {
rows=$1
s_start=$2
char=$4
str_st_row=$3
rows_end=$((str_st_row+rows))
for((i=str_st_row;i<rows_end;i++))
do 
tput cup $i $s_start
printf "$char " 
done
echo""
}

backslash() {
b_st_row=$1
b_st_cols=$2
b_char=$3
b_r_end=$((b_st_row + 5 ))
for((p=b_st_row;p<b_r_end;p++))
do 
tput setaf $4
tput cup $p $b_st_cols
printf "$b_char " 
((b_st_cols++))
done
echo""
}

forward() {
f_st_row=$1
f_st_cols=$2
f_len=$3
f_char=$4

f_r_end=$((f_st_row + $f_len))

for((i=f_st_row;i<f_r_end;i++))
do 
tput cup $i $f_st_cols
printf "$f_char "
 ((f_st_cols--))
done
echo""

}

horizontal() {
hrow=$2
hstart=$1
hcols=$3
char=$4

end=$((hstart + hcols))

for((i=hstart;i<=end;i++))
do 
tput cup $hrow $i
printf "$char" 
done
echo""
}

half_horizontal() {
hrow=$2
hstart=$1
hcols=$(($3/2))
char=$4

end=$((hstart + hcols))

for((i=hstart;i<=end;i++))
do 
tput cup $hrow $i
printf "$char" 
done
echo""
}

gen_rand() {
num1=$1

if [ $num1 -eq 0 ]
then
temp=$(($RANDOM % 2))
rand=$((temp + 2))

else

temp=$(($RANDOM % 5))
rand=$((temp + num1))
fi
}

two() {

hstart_2=$1
hrow_be=$2
hcols_2=$3
char=$4
color=$5

set_color

horizontal $hstart_2 $hrow_be $hcols_2 "$char"

st_row_2=$((hrow_be+1))
f_st_cols_2=$((hstart_2+hcols_2))

forward $st_row_2 $f_st_cols_2 5 "$char" $color
hstart_2_lo=$start
hrow_2_lo=$((hrow_be+6))
hcols_2_lo=5
horizontal $hstart_2_lo $hrow_2_lo $hcols_2_lo "$char"

}

zero() {

set_color

hstart_0=$((f_st_cols_2 +4))
hcols_0=5
horizontal $hstart_0 $hrow_be $hcols_0 "$char"

str_dwn_col_0=$hstart_0
str_dwn_row_0=$((hrow_be + 1))
str_dwn 6 $str_dwn_col_0 $str_dwn_row_0 "$char"

hstart_0_lo=$((f_st_cols_2 +4))
hcols_0_lo=6
hrow_0_lo=$((hrow_be+6))
horizontal $hstart_0 $hrow_0_lo $hcols_0 "$char"

str_dwn_col_rig_0=$((hstart_0 +5))
str_dwn_row_rig_0=$((hrow_be + 1))
str_dwn 6 $str_dwn_col_rig_0 $str_dwn_row_rig_0 "$char"
}

twoo() {
set_color

set_color

one() {
set_color
str_dwn_col_1=$((hstart_2 + 8))
str_dwn_row_1=$((hrow_be))
str_dwn 7 $str_dwn_col_1 $str_dwn_row_1 "$char"

}

five() {
set_color

set_color

#hstart_8=$((str_dwn_col_1 +4))
#hcols_8=5
#horizontal $hstart_8 $hrow_be $hcols_8 "$char"

str_dwn_col_8=$hstart_8
str_dwn_row_8=$((hrow_be + 1))
str_dwn 3 $str_dwn_col_8 $str_dwn_row_8 "$char"

hstart_8_lo=$((f_st_cols_2 +4))
hcols_8_lo=6
hrow_8_lo=$((hrow_be+6))
horizontal $hstart_8 $hrow_8_lo $hcols_8 "$char"

str_dwn_col_rig_8=$((hstart_8 +5))
str_dwn_row_rig_8=$((hrow_be + 1))
str_dwn 6 $str_dwn_col_rig_8 $str_dwn_row_rig_8 "$char"

hstart_8_lo=$((f_st_cols_2 +4))
hcols_8_lo=6
hrow_8_lo=$((hrow_be+3))
horizontal $hstart_8 $hrow_8_lo $hcols_8 "$char"

}

set_color(){
color=$RANDOM 
color=$((color%6))
tput setaf $color
}

cols=`tput cols`
mid=$((cols/2))
start=$((mid-16))
echo "What character do you want to use"
read char
#char="*"

tput clear
rows=5

begin_row=2
num_cols=6

two $start $begin_row $num_cols "$char" $color;zero;twoo;one

tput setaf 7
tput cup 9 0

Copy the script and save it as 2021.sh. Open a terminal and type

It will prompt for the characher which should be used. We have entered "*" as the characher, and you should see the output as shown below.

Extracting images from a PDF

2020-12-21T06:19:00.000-08:00

To extract images from a pdf document we can use the command

The syntax to use the command is

The above command will extract the images from page number 1 to page number 4 and the name of the images will be image-000.ppm ,image-001.ppm etc. The default format is ppm if the format of the file is to be changed, png option can be passed.

The above command will extract the images in the png format.

Package inputenc Error: Unicode character Σ (U+03A3) (inputenc) not set up for use with LaTeX.

2020-12-04T09:53:00.000-08:00

Running Pdflatex with math symbols not put inside proper math block can throw this error

In the above message the sigma symbol is being used outside the math block as shown below.

The solution is to put the equation into the math block, so surround the text with $ symbols and use the sum command which is the latex for sigma.

The error should not apper now on the usage of pdflatex .