CODEWITHSUNDEEP
linuxsed
user1190650
user1190650

Reputation: 3425

sed permission denied when overwriting file

I am trying to use sed to overwrite my index.php file, but I am getting an error:

$ sed -i 's@<head>@<head><script type="text/javascript" src="new.js"></script>@' index.php
sed: couldn't open temporary file ./sedmZNx8T: Permission denied

Does anyone know how to fix this?

Upvotes: 22

Views: 95055

Answers (10)

MRein
MRein

Reputation: 1

I had the same problem under Windows 10. I know, not the OPs question but maybe it helps other people comming from Google. The solution for me was to remove/move the folder I am working on from the randsomeware protected folders.

Upvotes: -1

Mikolaj
Mikolaj

Reputation: 61

I think there is a much easier solution. You can just print the file to the standard output and then use the sed on the stream. Afterward, you just redirect the stream to the same file. Obviously, it is a risky solution cause if you are not 100% sure that you know what you are doing you might lose the entire content of the file in question.

cat index.php | sed 's@<head>@<head><script type="text/javascript" src="new.js"></script>@' > index.php

Upvotes: 1

jbo5112
jbo5112

Reputation: 833

If the use of sed is not a hard requirement, you can probably use the highly ignored command ed.

ed -s index.php <<< $'%s@<head>@<head><script type="text/javascript" src="new.js"></script>@\nwq'

  • The <command> <<< '<my_input_string>' construct will pipe '<my_input_string>' into the <command> as standard input
  • The $'...' construct will be parsed for special characters. In this case the \n splits the string into two lines
  • You can use any construct you want to generate and pipe in the input (echo, printf, etc.)

Standard Input String:

%s@<head>@<head><script type="text/javascript" src="new.js"></script>@
wq

The first line is your regex search and replace as command for ed. The second line tells ed to write the changes and quit. You may recognize these commands from vi.

source: mrbluecoat.blogspot.com/2014/03/in-place-editing-right-way-hint-dont.html

Upvotes: 1

Welgriv
Welgriv

Reputation: 833

Short answer :

$ chmod +w .

And re-run sed.

Long answer :

As already said, the problem come from the fact that you don't have write permission on . (the current directory from which you run sed). If you are on your own machine/drive then you surely can give yourself the permission to write on this directory, that's what the chmod do here, unless you want protect it for some reason. However, if your on a network drive and can't change your permission on it then you should ask the one that own the directory to do it or use a workaround solution like copy-modify-past the file somewhere else.

Upvotes: 0

HexaCrop
HexaCrop

Reputation: 4293

check for the /tmp folder permission It should have the following permission

drwxrwxrwt   7 root root 4.0K Nov 16 15:06 tmp

If it is not ok for you then run the following commands

sudo chown root:root /tmp
sudo chmod 1777 /tmp

once this is done, then put a sudo infront of your sed command to execute the command as a root user.

This will solve the issue

Upvotes: 1

Ayvin
Ayvin

Reputation: 59

I think you can you "sudo" in front of your command. Like sudo sed -i 's/geteuid/getppid/g' /usr/bin/vlc It worked for me.

Upvotes: 5

Bishwas Mishra
Bishwas Mishra

Reputation: 1342

You need to have the write permissions to the folder whose file you are changing.

As explained here: https://stackoverflow.com/a/36404569/5381704

Upvotes: 1

Dan Miller
Dan Miller

Reputation: 311

Really no great answers here. Sorry if thread is dead, it came up in google searches and nothing really answered the question. Although altendky's answer is sort of the same as mine... There IS a workaround...find a world writable directory, say /tmp

cp /etc/file_to_mod /tmp
sed -i -e 's/foo/bar/g' /tmp/file_to_mod
cat /tmp/file_to_mod >/etc_file_to_mod

Hope that helps!

Upvotes: 15

altendky
altendky

Reputation: 4354

Given that you do not have write access to the directory where index.php is stored, then generally you would not have access to index.php...? Assuming this is a 'non-standard' case and you do have write access, sed -i is trying to create a temp file in the same directory as index.php (just checked and it is the same directory, not the CWD). Run sed without -i and end the line with something like > ~/sed.out to write the result into a file in your home directory. Then do what you will with that file.

sed 's@<head>@<head><script type="text/javascript" src="new.js"></script>@' index.php > ~/sed.out

Be aware that you while you can cp ~/sed.out index.php you can not mv ~/sed.out index.php. It would seem that cp will put the contents into index.php (not modifying the directory you do not have write permissions to) while mv tries to change the directory (that you don't have write permissions to).

Upvotes: 3

Gilles Qu&#233;not
Gilles Qu&#233;not

Reputation: 185630

Seems like you have a permission issue on the /tmp dir. (as discussed bellow, you run command in phpshell, so TMP dir can be setted elsewhere than /tmp)

It should looks like : 

$ ls -ld /tmp
drwxrwxrwx 333 root root 32768 12 oct.  03:13 /tmp/

explanations

When invoking sed with -i flag, sed create a temporary file in /tmp dir.

Proof with strace :

$ strace -f -e trace=file sed -i 's/a/z/' /tmp/a
execve("/bin/sed", ["sed", "-i", "s/a/z/", "/tmp/a"], [/* 94 vars */]) = 0
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
(...)
open("/tmp/sedPSBTPG", O_RDWR|O_CREAT|O_EXCL, 0600) = 4
rename("/tmp/sedPSBTPG", "/tmp/a")      = 0
+++ exited with 0 +++

Upvotes: 6

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