If I want to redirect not the stdio but as arguments the output of a program , should I use xargs?
For example, I do ls and I want the filenames to be arguments to the next command rather than an input stream.
Is there a good example of what I'm talking about? This example is superficial but illustrates what I mean: use the output from ls as arguments to cat for displaying the contents of the files.
First, do not parse ls. There are many reliable ways of getting file names but ls is not one of them.
The following uses the shell's globbing to generate file names and passes a nul-separated list of them to xargs which runs them through cat:
printf '%s\0' * | xargs -0 cat
I understand that the point of this was to demonstrate files->xargs. Otherwise, of course, unless there are too files to fit on a command line, the above can be replaced with:
cat *
Both ls and printf '%s\0' * will display all of a directory's contents, including its subdirectories. If you want to be more selective, say, including regular files but not subdirectories, then, as cas suggests, find is better tool:
find . -maxdepth 1 -type f -print0 | xargs -0 cat
Or:
find . -maxdepth 1 -type f -exec cat {} +
find has many useful options. See man find for details.
cat * can cause an arguments list too long error.
ls -t | head -1 to another command? based on your answer, I worked out printf '%s\0' "$(ls -t | head -1)" | xargs -0 gvim (needed the double quotes for filename having spaces).. tested a few cases, but not sure if this can open latest modified file for all sorts of filenames..
gvim "$(ls -t | head -1)".