FreeBSD sed error - I have permissions, but "Permission denied"

Question

Permissions:

ls -al file
-rwxrwxr-x  1 root  wheel 

User group:

groups
wheel 

If I do this:

sed -i'' -e '/Marker/i\'$'\n''text string'$'\n' file 

I get an error:

sed: ../file: Permission denied

But at the same time I can read, write and execute this file. As it shown in permissions.

Why sed is not working? I use the same User and the same file. Okay, owner is root, but I have read and write permissions

 uname -a
FreeBSD srv 11.0-RELEASE-p1 FreeBSD 11.0-RELEASE-p1 #0 r306420: Thu Sep 29 01:43:23 UTC 2016     root@releng2.nyi.freebsd.org:/usr/obj/usr/src/sys/GENERIC  amd64

Answer 1

sed -i'' -e ... file 

The BSD sed requires an argument to -i, as opposed to GNU sed that accepts an optional argument to it.

FreeBSD sed man page:

-i    extension     

Edit files in-place similarly to -I

vs. GNU sed man page:

  -i[SUFFIX], --in-place[=SUFFIX]

edit files in place (makes backup if SUFFIX supplied)

Note the brackets or lack of them.

Also, in shell -i'' is the same as just -i, the quotes surrounding an empty string are just removed.

So, what sed thinks you're asking is to create a backup file with the extension -e, and unless you have write permission to the directory, too, you won't be able to do that.

---

Even without an argument or with an empty argument to -i, sed will probably create a temporary file where it writes the resulting output before moving it to the original name. At least GNU sed creates the temporary file in the same directory as the original, so again you need to have write permission to that directory.

$ strace -etrace=open,rename sed -i -e '1d' foo
[...]
open("foo", O_RDONLY)                   = 3
open("./sedD9J9tV", O_RDWR|O_CREAT|O_EXCL, 0600) = 4
rename("./sedD9J9tV", "foo")            = 0

To work around that, you could create a temporary file elsewhere, and then move its contents to place:

$ sed -e '...' file > /tmp/file.tmp
$ cat /tmp/file.tmp > file && rm /tmp/file.tmp

Answer 2

So the problem was with parent path, where script is located. I think (I really dont know how sed works), sed tried to create a clon-file to add a text string and can't because of 755 path permissions. 775 solved the problem.