Sed gives "sed: 1: "tsunit.js": undefined label 'sunit.js'"

Question

Short questing, why does this line

sed -i '1s/^/#!\/usr\/bin\/env node\n/' tsunit.js;\

Give me this error

sed: 1: "tsunit.js": undefined label 'sunit.js'

in a Makefile, if relevant.

I’m on a Mac.

Answer 1

According to the Apple man page for sed, the -i option takes a required argument specifying the file extension for the backup file. As a result, assuming that you are on a Mac or similar, sed believes that you intended '1s/^/#!\/usr\/bin\/env node\n/' to be the file extension of the backup. It then interprets tsunit.js as a sed command. the leading t tells sed to branch to the label sunit.js which, of course, doesn't exist. Hence the error message.

The solution is:

sed -i '.bak' '1s/^/#!\/usr\/bin\/env node\n/' tsunit.js

Or, if you really do not want a backup:

sed -i '' '1s/^/#!\/usr\/bin\/env node\n/' tsunit.js

Answer 2

Also, it looks like you're inserting a line. sed has more commands than s

sed -i "" '1i\
#!/usr/bin/env node' tsunit.js