如何在awk命令中使用存储在变量中的数字

Question

I am attempting to have the script grab a random record from a file. The file has 10 total records. Not sure why what I currently have is not working. (I have ``around what n is equal to)

n=expr $RANDOM % 10 + 1 
awk 'BEGIN{RS = "%"} NR==$n' pathToFile

If I substitute $n for any number 1-10 there are no issues.

Answer 1

You can generate the random number within awk to avoid quoting challenges:

awk -v min=1 -v max=10 'BEGIN{srand() 
     n=int(min+rand()*(max-min+1))
}
#... the rest of the awk ...'

If you want to print a random record:

awk -v min=1 -v max=10 'BEGIN{srand() 
n=int(min+rand()*(max-min+1))
} 
NR==n {print; exit}' file

Or, you can generate and assign on the awk command line:

$ awk -v n=$(expr $RANDOM % 10 + 1) 'BEGIN{ print n }'

Or,

$ echo $n
7
$ awk -v n="$n" 'BEGIN{ print n }'
7

Answer 2

This should work the way you want:

awk 'BEGIN{RS = "%"} NR=="'"$n"'"' /folder/file

Note that the only difference from your code is the extra "'" "'" around the variable.