assign number of output lines to a variable

Question

How can I run a command from a bash script and at end print the number of lines it printed?

The awk equivalent would be

{ print; } 
END { print NR; }

I could only come up with the following. This works for now, but I can not get it outside the subshell.

| (lc=0; while read; do echo $REPLY; lc=$(($lc+1)); done; echo $lc)

UPDATE

Seems my problem was something quite different. I had first tried to use /dev/stdout which failed:

tester> { echo abc | tee /dev/stdout | wc -l;  } > /tmp/abc; cat /tmp/abc
2

This seemed to be because tee /dev/stdout gives error:

tester> echo abc | tee /dev/stdout
tee: /dev/stdout: Permission denied
abc

The answer by Jeff Schaller worked:

tester> { echo abc | tee >(wc -l);  } > /tmp/abc; cat /tmp/abc
abc
1

But this morning on retrying I saw it works!

tmp> echo abc | tee /dev/stdout
abc
abc

After spending some time I found two problems:

When |tee /dev/stdout failed yesterday I had logged in as usr1 done a sudo to another usr2, sudo su usr2. In this case the chain of soft link is /dev/stdout -> /proc/self/fd/1 -> /dev/pts/1 and the last one was owned by usr1. So the tee failed. Today I tried as usr1, so it succeeded.

But then I realized the other error with tee /dev/stdout, which is that all output goes to wc -l; line count is double and nothing is printed.

Answer 1

I'm not sure how the line-count could be printed any better:

$ seq 1 5 2>&1 | tee >(wc -l | { read lines; echo Lines of output: $lines; })
1
2
3
4
5
$ Lines of output: 5

This redirects the command's (here seq 1 5) stderr to stdout, so that tee sees both of those streams; tee then copies its input back out and also copies the input to a process substitution that runs wc -l to count the lines. I then read the output of wc into the $lines variable to provide a report.

Answer 2

Using sed:

some_command | sed -n 'p;$='

For example:

$ touch file.{a..k}
$ printf '%s\n' * | sed -n 'p;$='
file.a
file.b
file.c
file.d
file.e
file.f
file.g
file.h
file.i
file.j
file.k
11

The sed script will just copy the input to the output with the print command (p) applied to every line of input, but for the last line ($), it will also print the line number (=).

Answer 3

You can simply use your awk command :

echo -e "foo\nbar"| awk '{ print; }END { print NR; }'
foo
bar
2