awk: Columns are not printed when concatenating strings is passed as command string

Question

I've found some anomaly when writing a script.

The following examples works as expected:

$ echo 123 | awk '{print $1 456}'
123456
$ sh -c "echo 123 | awk '{print $1}'"
123

But the following example, doesn't:

$ sh -c "echo 123 | awk '{print $1 456}'"
456

I'm expecting to print the 1st column with the additional string, which should return 123456 as it does when running the same command withoutsh -c. But what is happening, the 1st column is ignored for some reason. What's interesting, $1 is printed without problems when not performing string concatenation.

Why this is happening and how to do string concatenation within the command which is passed to separate instance of shell?

Answer 1

You must escape $ sign:

$ sh -c "echo 123 | awk '{print \$1 456}'"
123456

Otherwise, $1 is expanded by current shell.