CODEWITHSUNDEEP
linuxbashshell
samuelbrody1249
samuelbrody1249

Reputation: 4767

How to create a file on the command line and pass as an argument to a command

I call a library like this:

# myFile.txt is a file that already exists read by `grun`
$ grun TestLexer tokens -tokens myFile.txt

However, instead of passing a file, I'd like to create/re-create that every time I run it in the command-line such as something like the following:

$ grun TestLexer tokens -tokens "echo 'x+1' > myFile.txt"

What would be the proper way to actually do that?

Upvotes: 0

Views: 889

Answers (2)

jhnc
jhnc

Reputation: 16662

Bash has process substitution.

You can run a command and make its output available to another command as if it were a file:

$ grun TestLexer tokens -tokens <(echo 'x+1')

To see what is happening, consider:

$ echo <(echo 'x+1')

grun reads from stdin if a filename is not provided, so you could also pass a here-doc / here-string, or pipe in the data:

$ grun TestLexer tokens -tokens <<<'x+1'

$ echo 'x+1' | grun TestLexer tokens -tokens

Upvotes: 6

Henrique Bucher
Henrique Bucher

Reputation: 4474

Would this be an option?

echo 'x+1' > myFile.txt && grun TestLexer tokens -tokens myFile.txt

or perhaps in the case that this can be run multiple times concurrently (in case myFile.txt would be overwritten) or you dont want to commit to a filename:

tmp=$(mktemp) && echo 'x+1' > $tmp && grun TestLexer tokens -tokens $tmp  && rm -f $tmp

Upvotes: 1

Related Questions