Shell Programming and Scripting

When you specify that awk is the shell to be used to interpret your script (i.e., #!/bin/awk -f), you can't have awk ' at the start of your script or ' at the end of it. (And, there shouldn't be a space after the #! even though some systems let you get by with that.) Try:

Code:

#!/bin/awk -f
NR==FNR {s=substr($2,6,7); a[s]=s; c[s]=s; next }
{s=substr($3,3,7); b[s]=s; c[s]=s }
END {for (i in c) if (a[i]!=b[i]) print i}

and invoke it with:

Code:

comp_host file1 file2

or

Code:

awk -f comp_host file1 file2

Note also that if you run it with the command:

Code:

> comp_host file1 file2

you run the risk of the redirection deleting the contents of comp_host if file1 is executable. (With some shells the redirection might be processed before the shell determines whether or not file1 is executable.)