How to convert to a zero byte file?

Question

HI,

in unix there are number of files in my directory. i want to change all the files to zero byte files. is that possible on a single command line?

for example:

-rw-r--r--   1 sumanma  dev          434 Jan  8 14:36 pprbc_NL.cpp
-rw-r--r--   1 sumanma  dev          488 Jan  8 14:37 pprbc_TreeBuild.cpp
-rw-r--r--   1 sumanma  dev          783 Jan  8 14:37 pprbc_UPDwm.cpp

i want to change these to

-rw-r--r--   1 sumanma  dev          0 Jan  8 14:36 pprbc_NL.cpp
-rw-r--r--   1 sumanma  dev          0 Jan  8 14:37 pprbc_TreeBuild.cpp
-rw-r--r--   1 sumanma  dev          0 Jan  8 14:37 pprbc_UPDwm.cpp

I am using tcsh

Answer 1

Yes you can.

Try this

for i in *
do
 echo -n > $i
done

(Assuming bash here but the basic idea is the echo).

Edit : One liner (bash). You'll need the semicolons etc. which you won't need in the multiline version.

 for i in * ; do echo -n > $i ; done

Edit: If you're stuck using tcsh, you can always invoke bash to run a one liner like so

 bash -c 'for i in * ; do echo -n > $i ; done'

Answer 2

I can't immediately think of an easy one-liner for tcsh.

Here is a three-liner:

foreach i (*)
  cat /dev/null > $i
end

You can type this in on the command line, i.e., it doesn't have to be a script. Unfortunately for one-liner purposes, and unlike the sh-series, the csh-derived shells parse the control structures by line, not by pipeline. This means that foreach i (*); echo $i; end won't work.

Of course, you could do a one-liner by switching shells for a line:

sh -c 'for i in *; do cat /dev/null > $i; done'

Answer 3

for file in *
do
   [ -f "$file" ] && >"$file"
done

Answer 4

For one file you can use

>file.cpp

For more then one you need a for loop as already described from others. If there is a directory in the current directory, then you recive an error message.

for f in *;do >$f;done

to avoid this use

for f in *;do [ -f $f ] && >$f;done