How to compare number of lines of two files using Awk - awk

Question

I am new to awk and need to compare the number of lines of two files.
The script shall return true,
if lines(f1) == (lines(f2)+1)
otherwise false. How can I do that?
Best regards

Answer 1

If it has to be awk:
awk 'NR==FNR{x++} END{ if(x!=FNR){exit 1} }' file1 file2
The varibale x is incremented and contains the number of line of file1 and FNR contains the number of file2. At the end, both are compared and the script is exited 0 or 1.
See an example:
user#host:~$ awk 'NR==FNR{x++} END{ if(x!=FNR){exit 1} }' shortfile longfile
user#host:~$ echo $?
1
user#host:~$ awk 'NR==FNR{x++} END{ if(x!=FNR){exit 1} }' samefile samefile
user#host:~$ echo $?
0

Answer 2

Something like this should suit your purposes:
[ oele3110 $] cat line_compare.awk
#!/usr/bin/gawk -f
NR==FNR{
n_file1++;
}
NR!=FNR{
n_file2++;
}
END{
n_file2++;
if(n_file1==n_file2){exit(1);}
}
[ oele3110 $] cat f1
1
1
1
1
1
1
[ oele3110 $] cat f2
1
1
1
1
1
[ oele3110 $] cat f3
1
1
1
1
1
[ oele3110 $]
[ oele3110 $] wc -l f*
6 f1
5 f2
5 f3
16 total
[ oele3110 $] ./line_compare.awk f1 f2
[ oele3110 $] echo $?
1
[ oele3110 $] ./line_compare.awk f2 f3
[ oele3110 $] echo $?
0
[ oele3110 $]
Actually, I think I should have asked you to invest a bit more effort before giving you the answer. I'll leave it for now, but next time I won't make the same mistake.