When experimenting with the ls -l command I noticed that in the /dev folder ls -l was sometimes printing something like this in the first column :  crw-rw----+   What is this "+"? What does it mean? The man page does not give any information about this.
67793
If the ls -l command gives me a permission string like  rwsr-s--x   What does the 's' mean? The only sources I found mention that it can be present sometimes but do not elaborate.  What does a '+' instead of a '-' mean? I have found mentions of 'extended permission' but nothing clear.
38522
I keep seeing parentheses and a number after a command in Unix or Linux or C function.   For example: man(8), ftok(2), mount(8), etc.  What do these mean? I see them in man too.
27342
In Linux, what does the d mean in the first position of drwxr-xr-x?  And what are all of the possible letters that could be there, and what do they mean?  I'm trying to learn more about the Linux file permissions system, and I'd like to see a list of the character meanings for the first slot.
48702
The output of ls -l command yields the following result:    What is the number field between file permission and owner? i.e. what are those 1, 1, 1, and 2? I checked the --help but that doesn't explain it.  [EDIT]  I thought it was the number of files in a directory but it isn't. See image. "tempFolder" has 3 files but still show a "2"
62288
This question was prompted by questions about ls' -1 option and the recurring tendency of people to ask question and answers that includes processing the output of ls.   This reuse of the output ls seems understandable, e.g.: if you know how to sort a list of files with ls you might want to use the output in that way as input for something else.  If those Q&amp;A don't include a reference to the file name list produced consisting of nicely behaving file names (no special characters like spaces and newlines), they are often commented upon by someone pointing out the danger of the command sequence not working when there are files with newlines, spaces etc.  find, sort and other utilities solve the problem of communicating "difficult" file names to e.g. xargs by using an option to separate the file names with the NUL character/byte which is not a valid character in file name (the only one in addition to /?) on Unix/Linux filesystems.  I looked to the man page for ls and the output for ls --help (which has more options listed) and could not find that ls (from coreutils) has an option to specify NUL separated output. It does have a -1 option which can be interpreted as "output file names separated by newline")  Q: Is there are technical or philosophical reason why ls does not have a --zero or -0 option that would "output file names separated by NUL"?  If you do something that only outputs the file names (and not use e.g. -l) that could make sense:  ls -rt -0 | xargs -r0 …   I could be missing something why this would not work, or is there an alternative for this example that I overlooked and that is not much more complicated and/or obscure.    Addendum:  Doing ls -lrt -0 probably does not make much sense, but in the same way that find . -ls -print0 does not, so that is not a reason to not provide a -0/-z/--zero option.
61890
I see stuff like command 1&gt; out or with 2&gt;&amp;1 to redirect stderr, but sometimes I also see &amp;&gt; by itself, etc.  What is the best way to understand &amp; and what it means exactly?
21492
Using the following command, could someone please explain what exactly is the purpose for the ending curly braces ({}) and plus sign (+)?  And how would the command operate differently if they were excluded from the command?  find . -type d -exec chmod 775 {} +
50485
I've noticed that sometimes wrapper scripts will use ${1:+"$@"} for the parameters rather than just "$@".  For example,  uses  exec "$binary" $opts ${1:+"$@"}   Can anyone break ${1:+"$@"} down into English and explain why it would be an advantage over plain "$@"?
32993
When I run ls -adl .* in one of my directories, I get a file that has this listing:  lrwxrwxrwx  1 user group   43 Jul  3 16:25 .#filename.py -&gt;   person@computer.edu.4018:1372874769   The filename and URL-looking thing are highlighted in red. What does the l mean in lrwxrwxrwx? What kind of file is this?
76072
In my terminal prompt definition in my .bashrc file, among other things, I have this snippet of code:  ${debian_chroot:+($debian_chroot)}   What does this do, and do I need it?
115808
I want to list the components of the current working directory in a text file  ls -1 &gt; textfile   Output looks fine with more.   1010661085645 1010729039145 1010747080245 1010849051345 1010859053445 1011046075845   However when I view this textfile with emacs, several strange characters appear  [0m[01;34m1010661085645[0m [01;34m1010729039145[0m [01;34m1010747080245[0m [01;34m1010849051345[0m [01;34m1010859053445[0m [01;34m1011046075845[0m   Can anyone explain what is going on here?
76617
What does ` mean in this output from lsblk?
78059
Example: In a Terminal command xdpyinfo | grep resolution (that I have taken from an answer), does the | character mean that the xdpyinfo output shall be sent to the grep program input for printing a line containing the resolution string? Where should I seek for such an information to avoid filling this forum by too simple questions? Thanks.
10017
I have compared the man pages of dir and ls and they seem to be exactly the same. Both are part of GNU coreutils and "list directory contents".   The only difference I've seen so far is that dir doesn't colorize the output.  So why do two commands exist? Is there a difference I missed? Why would one prefer dir over ls?
86602
Sometimes I see the following command:   find . -name  * -exec ls -a {} \;   I was asked to execute this.  What does {} \; mean here?
119826
On several Unix servers, I have seen below behavior:   I list all the files using ls -lrt: 3 files are being shown up  I open one of the files using vi editor  I close the open file   Now in some Unix system, I can still see the earlier screen as it is as in point 2 (listing those 3 files, ls -lrt output as it is) whereas on some systems, the text of recently opened file is printed.   I want to know which setting in profile or some *rc file this behavior depends.
59625
while reading about linux file searching I got the following...  To search for files using the * wildcard, replace the unknown string with *, e.g. if you remember only that the extension was .out, type ls *.out  and when I tried the following command on system(ubuntu 14.04 LTS) ..I got   anupam@JAZZ:~$ ls  *.bash*   ls: cannot access  *.bash* : No such file or directory  anupam@JAZZ:~$ ls  .bash*  .bash_history   .bash_logout  .bash_profile  .bashrc  anupam@JAZZ:~$   in the first case why it is showing No such directory ( *.bash* ) and in next case its showing the files ( .bash* )   I am new to this flavor, and according to my automata theory classes (*) means any combination of strings including epsilon(empty),,So why the results are different in both the cases....?