I have a question about setuid:
for example, there is a file - 1.txt, only root has write permission:
$ll 1.txt
-rw-r--r--. 1 root root 57 Jul 1 12:19 1.txt
For an ordinary user to modify the file, I did the following:
$ sudo chmod u+s /usr/bin/echo
$ ll /usr/bin/echo
-rwsr-xr-x. 1 root root 33128 Oct 31 2018 /usr/bin/echo
However, when the user ran below command, it still got permission error.
$ echo 111 > 1.txt
bash: 1.txt: Permission denied
Then I did a similar test on ls command：
Only root has write permission to test/ directory:
$ ll -d test/
drw-------. 2 root root 34 Jul 1 14:18 test/
a user that run ls command would report an error
$ ls test/
ls: cannot open directory test/: Permission denied
Then setuid on ls command:
$ sudo chmod u+s /usr/bin/ls
$ ll /usr/bin/ls
-rwsr-xr-x. 1 root root 117680 Oct 31 2018 /usr/bin/ls
after this, the user was able to run the command
$ ls test/
1 23 4
What's the difference between echo and ls? Or what I missed here?
I want to get a list of all directory permissions from current folder to /. For example, for the directory: /var/lib/program/subfolder, I want an output such as:
$ pwd
/var/lib/program/subfolder
$ magic_ls_-l_command somefile
drwxr-xr-x 10 root root 4096 May 15 20:20 var
drwxr-xr-x 10 root root 4096 May 15 20:20 lib
drwxrwxr-x 10 root user 4096 May 16 20:21 program
drwxrwxr-x 10 root user 4096 May 16 20:21 subfolder
-rwxrwxr-- 1 root user 4096 May 16 20:22 somefile
I don't care about the order (from /var to /subfolder or the other way around), the number of hard links or even the date. I just wrote them down to emulate the ls -l output. Also, I don't care how each filename in printed (/var and /lib, var and lib, or /var and /var/lib). I'm just interested in the ownership of each file/directory in the path from the choosen file or pwd to /.
In case I should install some program, I'm under Ubuntu 20.04.
This question has already been answered in superuser.com (I don't know if I can mark a question from one site as duplicate from another). The solution is as simple as writing (assuming I am in the same directory as the target filename):
$ namei -l $(pwd)/somefile ## or `namei -l $(realpath -s somefile)`
Because of -l, it lists basic permissions in long format for each parent directory.
I have to use pwd/realpath because namei doesn't resolve relative paths. If I'm not in the target directory, just write the full path.
I made this small script that does this. I use cd "$1"; pwd to get the current directory so that paths are not canonicalized (say, if you try magic-ls . and your current directory is /var/lib/postgres, but that is a symlink to /mnt/postgres, you will get /var, /var/lib and /var/lib/postgres, while using realpath you would get /mnt and /mnt/postgres)
magic-ls() {
local current=$(cd "$1"; pwd)
while [[ $current != '/' ]]; do
ls -ld "$current"
current=$(dirname "$current")
done
}
Here's an example output:
[leodag#desk ~]$ magic-ls
drwx------ 1 leodag leodag 2722 jun 21 13:49 /home/leodag
drwxr-xr-x 1 root root 18 mai 2 2019 /home
By the way it will also work with no argument since cd "" does not change your directory.
Edit: removed realpath from the while check, since that could lead to unexpected results if there was a link to / in the path, and was unneeded.
I wrote a bash script for you. It'll have some bugs, if you have space in names. If it bothers you, I'm happy for changes recommendations in the comments.
#!/bin/bash
if [ ! -z "$1" ] && [ -e "$1" ]
then
path=`realpath -s "$1"` # read argument as absolute path
else
path="$PWD" # No valid argument, so we take pwd
fi
paths=""
while [ "$path" != / ];do
paths+=" $path"
path=`dirname "$path"`
done
paths+=" $path" # Adding / to pathlist too
ls -ld $paths
With realpath -s you can catch the absolute path, but you wont follow the link. If no argument is given, we will use pwd as the file/directory to list.
We append each path to a list. This gives us the advantage of a better layout in the end, so that we get a nice table because we run ls only once.
Output:
bobafit:~$ magic_ls_-l_command /usr/bin/python3
drwxr-xr-x 21 root root 4096 Jun 20 10:07 /
drwxr-xr-x 14 root root 4096 Sep 5 2019 /usr
drwxr-xr-x 2 root root 110592 Jun 20 10:07 /usr/bin
lrwxrwxrwx 1 root root 9 Apr 7 12:43 /usr/bin/python3 -> python3.8
Just using parameter expansion:
#!/usr/bin/env bash
path="$1"
while test -n "$path"; do
ls -lLd "$path"
path="${path%/*}"
done
calling method :
bash test.sh /var/lib/program/subfolder/somefile
giving
-rw-r--r-- 1 root root 0 Jun 21 18:49 /var/lib/program/subfolder/somefile
drwxr-xr-x 1 root root 4096 Jun 21 18:49 /var/lib/program/subfolder
drwxr-xr-x 1 root root 4096 Jun 21 18:49 /var/lib/program
drwxr-xr-x 1 root root 4096 Jun 21 18:49 /var/lib
drwxr-xr-x 1 root root 4096 Jun 13 19:24 /var
#! /bin/bash
cur=""
IFS="/"
path=`pwd`
for dir in ${path:1}
do
cur=$cur/$dir
ls -lhd "$cur"
done
cur=$cur/$1
ls -lhd "$cur"
Terminal Session:
$ pwd
/tmp/dir_underscore/dir space/dir special #!)
$ ls
bash.sh test.txt
$ ./bash.sh test.txt
drwxrwxrwt 28 root root 36K Jun 21 22:45 /tmp
drwxr-xr-x 3 root root 4.0K Jun 21 22:27 /tmp/dir_underscore
drwxr-xr-x 3 root root 4.0K Jun 21 22:28 '/tmp/dir_underscore/dir space'
drwxr-xr-x 2 root root 4.0K Jun 21 22:54 '/tmp/dir_underscore/dir space/dir special #!)'
-rw-r--r-- 1 root root 0 Jun 21 22:29 '/tmp/dir_underscore/dir space/dir special #!)/test.txt'
This should possibly work:
pwd ; ls -lh ; while true ; do cd .. ; pwd ; ls -lh ; [[ "$PWD" == "/" ]] && break ; done
EDIT: I misunderstood the question at first. Try this:
(pwd ; ls -ldh ; while true ; do cd .. ; pwd ; ls -ldh ; [[ "$PWD" == "/" ]] &&
break ; done ; cd "$START")
EDIT2: fillipe's answer is probably the best, but here's my third and last attempt, which works on both files and directories:
magic_ls() {
fname="$1"
while true ; do
ls -lhd "$fname"
[[ "$fname" == "/" ]] && break ;
fname=$(dirname $(readlink -f "$fname"))
done
}
Just my 2 cents. My mac doesn't have the namei command (perhaps homebrew has a copy), but wanted to whip up a quick version that aligned the output in top-down order
#!/usr/bin/env bash
path="${1%/}"
DIRS=()
while test -n "$path"; do
DIRS=( "$path" "${DIRS[#]}" )
path="${path%/*}"
done
ls -ld "${DIRS[#]}"
Example output:
$ lspath $TMPDIR
lrwxr-xr-x# 1 root wheel 11 Oct 5 2018 /var -> private/var
drwxr-xr-x 7 root wheel 224 Jul 16 2020 /var/folders
drwxr-xr-x# 3 root wheel 96 Apr 5 2018 /var/folders/0c
drwxr-xr-x# 5 me staff 160 Apr 5 2018 /var/folders/0c/2_s_qxd11m3d1smzqdrs3qg40000gp
drwx------# 255 me staff 8160 Oct 7 09:18 /var/folders/0c/2_s_qxd11m3d1smzqdrs3qg40000gp/T
I had a directory with number of files and need to check the count of files present in it.
I tried the following two commands:
ls | wc -l
ls -l | wc -l
and found there are differences while using both commands. (ie. number of files is greater in the usage of second command while comparing to the first command.)
I would like to know the changes happening in the both commands.
From man ls:
-l (The lowercase letter ``ell''.) List in long format. (See below.) If the output is to a terminal, a total sum for all the file sizes is output on a line before the
long listing.
So ls -l adds a header line stating the "total" size of files:
$ ls -l /
total 65
-r--r--r-- 1 root wheel 6197 May 11 21:57 COPYRIGHT
drwxr-xr-x 2 root wheel 1024 Jun 1 16:02 bin
drwxr-xr-x 9 root wheel 1536 Jun 1 16:02 boot
dr-xr-xr-x 8 root wheel 512 Jul 7 20:16 dev
.......
$ pwd
/home/Thomas/Utveckling/Cgreen/thoni56/cgreen
$ realpath .
/cygdrive/c/Users/Thomas/Utveckling/Cgreen/thoni56/cgreen
$ cygpath -a .
/cygdrive/c/Users/Thomas/Utveckling/Cgreen/thoni56/cgreen/
Why is this? Why is absolute path from the root /cygdrive and not /?
How do I get an absolute path that starts with /home from a relative path, such as .., if I'm in that tree?
It is the effect of the presence of a link in the path.
Eg:
ls -ld /pub /tmp
lrwxrwxrwx 1 marco Administrators 19 Jun 26 2014 /pub -> /cygdrive/e/cyg_pub
drwxrwxrwx+ 1 marco Administrators 0 May 2 17:49 /tmp
$ realpath /pub /tmp
/cygdrive/e/cyg_pub
/tmp
It is possible to make a symbolic link between two symbolic link ?
like this:
root # ls -al /usr/sbin/ash
lrwxrwxrwx 1 root root 17 Mar 23 20:59 /usr/sbin/ash -> /usr/sbin/busybox
root # ls -l /bin/sh
lrwxrwxrwx 1 root root 13 Mar 23 21:00 /bin/sh -> /usr/sbin/ash
Yes, it's possible. You can create them like that:
ln -s /usr/sbin/busybox /usr/sbin/ash
ln -s /usr/sbin/ash /bin/sh