How to delete the contents of all the files in a directory

Question

Under /tmp/REPORTS I have a hundred files. What I want to do is erase the contents of each file in /tmp/REPORTS (not delete them). So I tried the following, but I get this error:

cp /dev/null /tmp/REPORTS/*

cp: Target /tmp/REPORTS/…..  must be a directory
Usage: cp [-f] [-i] [-p] [-@] f1 f2
      cp [-f] [-i] [-p] [-@] f1 ... fn d1
      cp -r|-R [-H|-L|-P] [-f] [-i] [-p] [-@] d1 ... dn-1 dn

How can I clear the contents of all the files in the directory?

Just to clarify - you want to move the contents of `/tmp/Reports` to another location? — ILostMySpoon, Mar 24 '15 at 17:08
no , only I want is to clear the files content under REPORTS dir , not to move them — maihabunash, Mar 24 '15 at 17:09
If you have GNU goodies, the fastest might be this: `truncate --size 0 /tmp/REPORTS/*`. — gniourf_gniourf, Mar 24 '15 at 17:10

score 2 · Accepted Answer · edited May 23 '17 at 11:58

2

Assuming that you mean you want to truncate the contents of each file, you can do this:

for file in /tmp/REPORTS/*; do > "$file"; done

This will clear the contents of each file in the directory.

As gniourf_gniourf has suggested in the comments above, there is a GNU tool truncate that can do the job for you as well:

truncate --size 0 /tmp/REPORTS/*

This will possibly be quicker than looping through the files manually.

edited May 23 '17 at 11:58

Community

1
1

answered Mar 24 '15 at 17:10

Tom Fenech

72,334
12
107
141

isnt not better to do --> for file in /tmp/REPORTS/*; do cp /dev/null "$file"; done – maihabunash Mar 24 '15 at 17:19
@maihabunash if you want to empty each file, this is the standard way to do it. – Tom Fenech Mar 24 '15 at 17:20
1

ok , btw in many linux/solaris the command truncate not defined , so I will choose the first option , and +1 for you – maihabunash Mar 24 '15 at 17:22
Actually, it would only clear the first byte of the file. OP asked to overwrite the file's contents with 0's. – Thomas Dickey Mar 25 '15 at 00:29
For `truncate`, the manpage hints that blocks which were part of the file before are still present on the filesystem, containing the unerased data. – Thomas Dickey Mar 25 '15 at 00:35

score 1 · Answer 2 · answered Mar 25 '15 at 00:55

The question appears to be asking for what is termed a "secure erase".

While you cannot cp /dev/null, you could get the effect you are asking about using dd. Here is a script to illustrate:

#!/bin/sh
for name in $*
do
    test -h "$name" && continue
    test -f "$name" || continue
    blocks=`ls -s "$name" | awk '{print $1; }'`
    dd if=/dev/zero of="$name" count=$blocks
done

The script

checks to ensure that the parameter is a regular file.
then it asks for the number of blocks for the file.
finally, it uses dd to copy 0's from the special device /dev/zero.

This relies on dd and ls having the same notion of blocksize (which appears to be the case). It also assumes that the filesystem does not reallocate blocks for a given file, i.e., that they can be reliably overwritten in-place. If you want a better guarantee, there are other solutions, e.g., this discussion of Secure Erase in UNIX

Soheil · Answer 3 · 2015-03-24T17:26:17.053

0

you can use this
for remove

find /tmp/REPORTS/ -type f -name "*.*" -exec rm -rf {} \;

or move them to some where you want for cp

find /tmp/REPORTS/ -type f -name "*.*" -exec cp {} \tmp\{} \;

for mv

find /tmp/REPORTS/ -type f -name "*.*" -exec mv {} \dev\null \;

edited Mar 24 '15 at 17:26

answered Mar 24 '15 at 17:09

Soheil

837
8
17

I dont whant to delete the files , what I need is to erase them as cp /dev/null , – maihabunash Mar 24 '15 at 17:15
You mean: `-exec cp /dev/null {} \;` and your `-name "*.*"` is (wrong and) useless. – gniourf_gniourf Mar 24 '15 at 17:27
see my answer i know that ! – Soheil Mar 24 '15 at 17:28

score 0 · Answer 4 · answered Apr 21 '15 at 02:13

0

Try this instead:

$ find /tmp/REPORTS/ -type f -exec cat /dev/null > {} \;

Or if you have a large number of files, try using \+ instead of \; for a more efficient commandline.

answered Apr 21 '15 at 02:13

James McPherson

2,476
1
12
16

How to delete the contents of all the files in a directory

4 Answers4