Try running /opt/homebrew/bin/brew shellenv by itself to see what output it produces. Returns exit status of command or success if command is null. Run PDFinfo again, this time piping the output to the FIND filter and then redirecting the output to a text file.
In the command prompt window, enter the following command: pdfinfo test.pdf View the output in the command prompt.
#Pdfinfo inside unix shell pdf#
In this case, running /opt/homebrew/bin/brew shellenv returns a bunch of text like var=value and eval runs them in your current shell, thus setting those variables to the required values.Ĭombine ARGs into a single string, use the result as input to the shell, I installed pdfinfo with Homebrew Cask: brew cask install pdfinfo. Run the PDFinfo utility on the sample PDF file. Consider the example of adding two numbers to find their sum. You can access the first parameter inside the script using 1, the second using 2 and so on. When used with eval, it causes your shell to execute the output. 8 Unix Shell Scripting Interview Questions With Sample Answers. This is an old, obsolete form of command substitution, supported for legacy reasons but shouldn't be used in new scripts. I often use commands like the following to remove old kernel packages from my Debian system: apt-get purge $(dlocate -k | grep '6\.0\.0-')īTW, you may also see scripts using backticks (`) for this.
The command inside the parentheses may be as simple or as complex as you need, from a single program to a long pipeline of commands. (ok, yeah, printf is a contrived example because just running date +%B produces the same output.but it does demonstrate how it works). Or to use the output of one program as args for another, e.g. It first tries to find the users private config file, /.xpdfrc. It's often used to get the output of a program into a variable. Pdfinfo reads a configuration file at startup. It executes the command inside the parentheses and returns the output of that command.
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