[SOLVED] How to use sed command to dynamically insert line number

sncak · 02-18-2021, 05:39 AM

I am trying to dynamically update sed line number using variable

and I am using the script

Code:

#!/bin/bash

FILE=$(awk 'NR==1{print $1}' log.txt)      #getting File path from log file
LINE=$(awk 'END{print}' log.txt)           #getting Line number from log file
cat $FILE > comp1
clear
sed -i "$LINEs/asm/asm-generic/" $FILE     #sed not working properly
cat $FILE > comp2
clear
echo "Done"
diff comp1 comp2

exit 0

I am getting no error but the substitution is no happening and code getting exited with no errors.

shruggy · 02-18-2021, 05:46 AM

How do you know that this

Code:

LINE=$(awk 'END{print}' log.txt)

gets the line number? It just saves the last line of log.txt to LINE.

Output the value of LINE before the sed command to see what it actually contains:

Code:

echo "|$LINE|"

More importantly, judging from your other thread, I suspect this is an example of XY problem.

Isn't finding all the relevant places in source where asm must be changed to asm-generic easier than evaluating the build log?

sncak · 02-18-2021, 06:07 AM

My log.txt file looks like this

Code:

/usr/src/linux-headers-5.10.16-olimex/include/asm-generic/bitops/non-atomic.h
5

and I am setting data in first-line to FILE variable and Second to Line variable.

berndbausch · 02-18-2021, 06:08 AM

Quote:

Originally Posted by sncak

Code:

sed -i "$LINEs/asm/asm-generic/" $FILE     #sed not working properly

To be honest, I don't understand the script, but the sed line doesn't work because you use a shell variable named LINEs. Most probably, the intention is

Code:

sed -i "${LINE}s/asm/asm-generic/" $FILE     #sed working properly

berndbausch · 02-18-2021, 06:12 AM

I would use tail to retrieve the last line from log,txt. If the first line in log.txt just contains the file to be edited, I would use head for that.

sncak · 02-18-2021, 06:13 AM

Quote:

Originally Posted by berndbausch

To be honest, I don't understand the script, but the sed line doesn't work because you use a shell variable named LINEs. Most probably, the intention is

Code:

sed -i "${LINE}s/asm/asm-generic/" $FILE     #sed working properly

thanks, working fine now.

boughtonp · 02-18-2021, 06:15 AM

Quote:

Originally Posted by sncak

How to use sed command to dynamically insert line number

Quote:

Originally Posted by sncak

I am trying to dynamically update sed line number using variable

Those are not the same thing, and neither one matches what the code appears to be trying to do.
It's almost always a good idea to provide brief example inputs and outputs, to clarify what you're actually trying to do.

Quote:

Code:

FILE=$(awk 'NR==1{print $1}' log.txt)      #getting File path from log file
LINE=$(awk 'END{print}' log.txt)           #getting Line number from log file

What does log.txt look like?

Quote:

cat $FILE > comp1

Why not cp "$FILE" comp1 ?

Quote:

sed -i "$LINEs/asm/asm-generic/" $FILE #sed not working properly

Sed is not the problem.

What do you think the LINEs variable contains...?

Also, always wrap filename variables with quotes.

edit: ok, I'm way too slow... how did typing that take 8+ minutes? :'(

shruggy · 02-18-2021, 06:31 AM

And even more importantly, the Linux sources for kernel 5.10.16 still have arch/arm/include/asm and arch/arm/include/uapi/asm. Why are you trying to change this to asm-generic? All you need is to specify the correct include path in the -I flag to compiler.