awk error: each rule must have a pattern or an action part

Question

From here I got the following command:

awk '/em1/ {i++; rx[i]=$2; tx[i]=$10}; END{print rx[2]-rx[1] " " tx[2]-tx[1]}' \
<(cat /proc/net/dev; sleep 1; cat /proc/net/dev)

which is fully working as intended. However, I would the output in Mbps, so I created 2 commands, one for upload, one for download (both working):

awk '/^e/ {i++; rx[i]=$2}; END{printf("%.2f Mbps", \
((rx[2]-rx[1])/1024/1024))}'  <(cat /proc/net/dev; sleep 1; \
cat /proc/net/dev)  # download

awk '/^e/ {i++; tx[i]=$10}; END{printf("%.2f Mbps", \
((tx[2]-tx[1])/1024/1024))}'  <(cat /proc/net/dev; sleep 1; \
cat /proc/net/dev)  # upload

But when I tried to combine then, but some errors came up:

$ awk '/^e/ {i++; rx[i]=$2}; tx[i]=$10}; \
END{printf(" down: %.2f Mbps, up: %.2f Mbps", \
((rx[2]-rx[1])/1024/1024)), ((tx[2]-tx[1])/1024/1024))}' \
<(cat /proc/net/dev; sleep 1; cat /proc/net/dev)

awk: cmd. line:1: /^e/ {i++; rx[i]=$2}; tx[i]=$10}; END{printf(" down: %.2f Mbps, up: %.2f Mbps", ((rx[2]-rx[1])/1024/1024)), ((tx[2]-tx[1])/1024/1024))}
awk: cmd. line:1:                                ^ syntax error
awk: cmd. line:1: each rule must have a pattern or an action part
awk: cmd. line:1: /^e/ {i++; rx[i]=$2}; tx[i]=$10}; END{printf(" down: %.2f Mbps, up: %.2f Mbps", ((rx[2]-rx[1])/1024/1024)), ((tx[2]-tx[1])/1024/1024))}
awk: cmd. line:1:                                                                                                           ^ syntax error
awk: cmd. line:1: /^e/ {i++; rx[i]=$2}; tx[i]=$10}; END{printf(" down: %.2f Mbps, up: %.2f Mbps", ((rx[2]-rx[1])/1024/1024)), ((tx[2]-tx[1])/1024/1024))}
awk: cmd. line:1:                                                                                                                                      ^ syntax error

I tried to solve it using sprintf, but the result was the same.

OS: Linux 4.0.5-1-ARCH x86_64 GNU/Linux

awk: GNU Awk 4.1.3, API: 1.1 (GNU MPFR 3.1.2-p11, GNU MP 6.0.0)

Answer 1

The errors, as awk helpfully (though verbosely) tells you

awk: cmd. line:1: /^e/ {i++; rx[i]=$2}; tx[i]=$10}; END{printf(" down: %.2f Mbps, up: %.2f Mbps", ((rx[2]-rx[1])/1024/1024)), ((tx[2]-tx[1])/1024/1024))}
awk: cmd. line:1:                                ^ syntax error
awk: cmd. line:1: each rule must have a pattern or an action part
awk: cmd. line:1: /^e/ {i++; rx[i]=$2}; tx[i]=$10}; END{printf(" down: %.2f Mbps, up: %.2f Mbps", ((rx[2]-rx[1])/1024/1024)), ((tx[2]-tx[1])/1024/1024))}
awk: cmd. line:1:                                                                                                           ^ syntax error
awk: cmd. line:1: /^e/ {i++; rx[i]=$2}; tx[i]=$10}; END{printf(" down: %.2f Mbps, up: %.2f Mbps", ((rx[2]-rx[1])/1024/1024)), ((tx[2]-tx[1])/1024/1024))}
awk: cmd. line:1:                                                                                                                                      ^ syntax error

are that closing } because you already closed that action block at rx[i]=$2}; before that and the , and the final ) because the printf call was already closed. The complete function call is this:

printf(" down: %.2f Mbps, up: %.2f Mbps", ((rx[2]-rx[1])/1024/1024))

So the , and everything that follows it is a syntax error because it isn't a valid statement on its own.