create a temporary file in a command line call

I really would like to know why someone votes -1 for this ?

I have found that since this board is used by people with different skill levels, some may encounter difficulty with a certain command and quickly vote it down. Though I found your command to work, I also have to say that there is a huge speed penalty associated with it. Perhaps not the best application, but as a way to show our fellow commandlinefu readers and contributors that your command works, here is my example:

time wc -l <

10675

real 0m0.497s

user 0m0.001s

sys 0m0.027s

time wc -l /etc/services

10676 /etc/services

real 0m0.006s

user 0m0.003s

sys 0m0.000s

Let me try to post the two commands again:

'time wc -l <

'time wc -l /etc/services'

Hope it works this time.

# time wc -l <

# time wc -l /etc/services

yes I have to agree that there is a huge speed penatly when useing this command. But I also have to say that for bash scripts that use mysql this is the best method that worked for me without using the mysql shell.

One could call it 'quick and dirty' but if you use it for bash scripts that are called every x hours, the speed penalty can be neglected I think.

Hum... Why dont simply use stdin ? oO

COUNT(*)

9

For bash you should use

works on zsh as well

let's try again:

works on zsh as well

Isn't this exactly the same as using a pipe? The

The process substitution is useful when you want to put some command's output into any_script.sh but any_script.sh won't take standard input for that particular function, only a filename. I've come across this a few times, I think with mplayer in one case.

There's the similar >(some command) too, which provides a fifo to any_script.sh by filename and any_script.sh can thereby write to the input of some command.

For some reason a lot of what I just posted disappeared...

Isn't this exactly the same as using a pipe? The

runs some command and connects its output to a fifo whose path is substituted into the command line, looking to any_script.sh as a filename.

But then you're using the < to redirect the contents of the file (the fifo) to the standard input of any_script.sh.

This is exactly the same as using a pipe like this:

The process substitution is useful when you want to put some command's output into any_script.sh but any_script.sh won't take standard input for that particular function, only a filename. I've come across this a few times, I think with mplayer in one case.

There's the similar >(some command) too, which provides a fifo to any_script.sh by filename and any_script.sh can thereby write to the input of some command.

all of you are right, BUT you can do things with this syntax you can not do with pipes.

This sample script does need a command file, a userfile and a directory with placeholer.

command file describes commands to excute one after another.

userfile contains usernames on a line.

Now the script reads in all those things and executes all commands in the command file in all diretorys whith all %U being replaced by usernames and alls %d being replaces by a diretory.

Now you see this script takes 2 files as argument which are created in background. I thinks you can't do such things with pipes. Maybe with named pipes but I don't know much about them.

By using this syntax you /are/ using named pipes. Read the "process substitution" section of the bash manual.

You're right that you can't do the command in your last comment using normal pipes -- I am not disputing that.

But my objection is in regard to the original command you posted. Let me explain again. The command you posted:

The

gets substituted with the path to the fifo which is set up so you're left with something like

where /dev/fd4 is the fifo connected to the output of

So /dev/fd4 is being redirected as *standard input* to any_script.sh -- its path is not being passed as an argument.

You can do this with a normal pipe, like

The process substitution is only needed when you want the fifos which are set up to be passed as arguments to a command.