CODEWITHSUNDEEP
node.jslinuxshellunix
Hoa
Hoa

Reputation: 20448

Why is 'sh -c' returning a different result from my actual command?

I'm trying to get the number of pages in a PDF file through the command line.

pdfinfo "/tmp/temp.pdf" | grep Pages: | awk '{print $2}'

produces

3

In Node.js, I need to use 'sh' because of the piping.

But

sh -c "pdfinfo '/tmp/temp.pdf' | grep Pages: | awk '{print $2}'"

produces

Pages:          3

Why am I getting different output?

Upvotes: 0

Views: 44

Answers (1)

Eric Renouf
Eric Renouf

Reputation: 14510

The sh -c command is double quoted, which will expand the $2 which is likely empty, so the awk command becomes just print which prints the whole line. You could escape the $ to prevent it from being expanded:

sh -c "pdfinfo '/tmp/temp.pdf' | grep Pages: | awk '{print \$2}'"

Incidentally, awk can do pattern matching, so no need for both grep and awk:

pdfinfo "/tmp/temp.pdf" | awk '/Pages:/ {print $2}'

Upvotes: 2

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