xargs can be used when you need to take the output from one command and use it as an argument to another. In your first example, grep takes the data from standard input, rather than as an argument. So, xargs is not needed. xargs takes data from standard input and executes a command. By default, … Read more
Use -I option: echo prefix | xargs -I % echo % post Output: prefix post
I ran across a similar issue and found this thread on search for an answer: Signal 13 means something is written to a pipe where nothing is read from anymore (e.g. see http://people.cs.pitt.edu/~alanjawi/cs449/code/shell/UnixSignals.htm ). The point here is that the ls command as executed by xargs is still writing output when the following head command … Read more
General method xargs -n 1 sh -c ‘<your_command> $0 || exit 255’ < input Specific case xargs -n 1 sh -c ‘curl –silent –output /dev/null \ –write-out “%{url_effective}: %{http_code}\n” $0 || exit 255’ < pages.txt Explanation For every URL in pages.txt, executes sh -c ‘curl … $0 || exit 255’ one by one (-n 1) … Read more
Does one of your filenames have a quote in it? Try something like this: find . “(” -name “*.m” -or -name “*.h” “)” -print0 | xargs -0 wc -l The -print0 argument tells find to use the NULL character to terminate each name that it prints out. The -0 argument tells xargs that its input … Read more
The solution: -I -I lets you name your argument and put it anywhere you like. E.g. ls | xargs -n 1 -I {} echo prefix_{} (replace {} with any string)
Use GNU Grep’s –null Flag According to the GNU Grep documentation, you can use Output Line Prefix Control to handle ASCII NUL characters the same way as find and xargs. -Z –null Output a zero byte (the ASCII NUL character) instead of the character that normally follows a file name. For example, ‘grep -lZ’ outputs … Read more
As I was about to complete writing this question, I ran parallel –version to report the version, only to find: WARNING: YOU ARE USING –tollef. IF THINGS ARE ACTING WEIRD USE –gnu. It is not clear to me why that flag is set by default. Needless to say, using –gnu worked! Thought I would post … Read more
You will get a nasty surprise when the number of files increase to more than one xargs command: Then you will first make a tar file of the first files and then overwrite the same tar file with the rest of the files. GNU tar has the –exclude option which will solve this issue: tar … Read more
There are two ways that I’ve found. The first is probably more idiomatic PowerShell, and the second is more true to the pipe-based spirit of xargs. As an example, let’s say we want to pass all our cat pics to myapp.exe. Method #1: Command substitution You can do something similar to using $(command substitution) in … Read more