I have a few servers with an application for some clients, and I want to make an application available for the client to view the server and application status, and to be able to restart some services.

I already have done the major part of it, replacing the login shell of a ssh user with a custom shell script that presents him a menu with some options to do that. The menu is launched automatically with sudo (with NOPASSWD) once he logs in, because the script needs to restart system services. The problem is that I'd like him to view the output of top or htop, but I don't want him being able to kill or renice processes and maybe other things that both top and htop permits. I just want him viewing the output of top.

Is there any option, flag or equivalent command?

I know I can specify mounts in fstab by either putting their path (like /dev/sda1 or /dev/mapper/myvg-logicalVolume1) or by fs label (LABEL=root) or by UUID (UUID=1234-5678-...).

I see a clear advantage in terms of reliability using the UUID for "classic" partitions like /dev/sda1, because if you repartition your drive/more partitions around/add more disks it may be that your some of your partitions now it gets recognized with another name, although mounting by UUID is more difficult to tell in which partition/LV your data is being stored.

But using LVM, my guts tell me that the LVM system itself manages the discovery of their disks/partitions and it doesn't matter if some PV is (after playing with partitions/disk) now named different. So there won't be any difference (speaking of reliablity) mounting by UUID or using the path like /dev/mapper/vg-lv, and the latter is more clear.

Is this correct?

I have a script that asks some questions to the user and repeats the question until the user has answered something appropiate. This is done with an infinite loop that is break'd when an acceptable answer is read:

while true
do
    read -p "Which helper do you prefer (cache, store)? " HELPER
    if [ "$HELPER" = "store" -o "$HELPER" = "cache" ]
    then
        break
    else
        error "Invalid option. Choose again"
    fi
done

This is working fine when called independently. The problem is when I execute this script inside a | while read ... loop:

# find scripts that should be run as non-root user, and run them all sequentially
grep -l '^\s*require_non_root' [0-9]* | while read execScript
do
  echo "=== EXECUTING $execScript ==="
  "./$execScript"
done

The ouptut of the grep command alone is what should be in my case:

15-gitcredentials
20-workspace
40-download_latest_dev_vapp
99-change_username_and_password

Problem:

the 15-gitcredentials script (the first snip I posted is part of this script) is reading the same STDIN that the | while read execScript part is expected to read, i.e. the output of the grep command. How could I made the 15-gitcredentials script to read not from STDIN but from other descriptor?

I am using nginx as reverse proxy and I have 2 rules like:

location ~ ^/indirect {
  rewrite ^/indirect(.*) /foobar$1;
}

location ~ ^/foobar {
  set $url http://example.com/something/index.php?var1=hello&access=$scheme://$host$uri;
  proxy_pass $url;
}

So, as you can see I'm passing the $uri variable as a parameter to the proxied page (the $uri variable is an nginx one, see the http core module documentation).

Problem is, if I visit http://example.com/foobar/hello%20world, the $uri variable contains /foobar/hello world (as you see, the %20 has been substituted with its url-decoded value, a space). And then, nginx returns http status code 400 (bad request) before executing the proxy_pass line (the backend there is not contacted).

There is also available the variable $request_uri, which holds the original request URI as issued by the client, so in this case it would hold the correct value, with the %20 sequence. But I cannot use this because if a client goes through the /indirect path, $request_uri would contain /indirect/... while I want that the access param passed to the backend be always /foobar/....

There are multiple indirect-like rules (this is for a DAV/calDAV/cardDAV server, and there are multiple clients out there that connect to multiple paths, so I need these indirect-like rules), so it is not feasible to do the proxy_pass there, and there are clients that go directly to the /foobar path.

So is there any way to get $uri without url-decoding it?

possible things that aren't acceptable:

• sending the request double-encoded, as the request may come from a client I have no control of
• specifying the final url multiple times in eacy indirect rule and also in the "direct" one, as it causes maintenance problems.

I've been working to have a script in a centralized server to do some things and output a .tar.gz file (see redirect temporarily STDOUT to another file descriptor, but still to screen). I also have exchanged ssh keys, so now from a client machine I can execute the script in my main server and output the result to a .tar.gz file in the client while seeing all the other output (STDERR) of the script:

me@client:~$ ssh auto@remoteserver /usr/local/bin/myscript.sh > content.tar.gz
// shows the output of the STDERR here...

me@client:~$ tar ztf content.tar.gz
content/file.txt
content/foobar.txt
...

But if I force the execution of this command putting the command option in the ~/.ssh/authorized_keys:

#/home/auto/.ssh/authorized_keys file
command="/usr/local/bin/myscript.sh",from="client" ssh-rsa 0UYmshd5FSDFf2fd...

and execute the following, it does not work:

me@client:~$ ssh auto@remoteserver > content.tar.gz
// shows **NOTHING**

me@client:~$ tar ztf content.tar.gz
gzip: stdin: not in gzip format
tar: Child returned status 1
tar: Error is not recoverable: exiting now

if I look into the file, it contains both the STDERR and the STDOUT. Any idea why it is getting mixed? And more importantly, any idea on how to avoid this?

ps: I should mention that myscript.sh is a wrapper for the main script, that basically calls the main script with a set of fixed params:

#!/bin/sh
# myscript.sh: wrapper for mainscript.sh to use by the user auto with ssh-keys
/usr/local/bin/mainscript.sh foo bar

I'm making a script that executes some commands inside, and these commands show some output on STDOUT (and STDERR as well, but that's no problem). I need that my script generates a .tar.gz file to STDOUT, so the output of some commands executed in the script also go to STDOUT and this ends with a not valid .tar.gz file in the output.

So, in short, it's possible to output the first commands to the screen (as I still want to see the output) but not via STDOUT? Also I would like to keep the STDERR untouched so only error messages appear there.

A simple example of what I mean. This would be my script:

#!/bin/bash

# the output of these commands shouldn't go to STDOUT, but still appear on screen
some_cmd foo bar
other_cmd baz

#the following command creates a tar.gz of the "whatever" folder,
#and outputs the result to STDOUT
tar zc whatever/

I've tried messing with exec and the file descriptors, but I still can't get it to work:

#!/bin/bash

# save STDOUT to #3
exec 3>&1

# the output of these commands should go to #3 and screen, but not STDOUT
some_cmd foo bar
other_cmd baz

# restore STDOUT
exec 1>&3

# the output of this command should be the only one that goes to STDOUT
tar zc whatever/

I guess I'm lacking closing STDOUT after the first exec and reopen it again or something, but I can't find the right way to do it (right now the result is the same as if I didn't add the execs

In /bin/sh and /bin/bash (and I guess a lot of other shells), starting scripts with #!/bin/sh -e (or executing set -e in someplace in the script) would cause the script to abort when any command line inside the script exits with a status code different than 0.

Is there any equivalent or workaround to get the same behavior in a perl script? (i.e. if any instruction generates an error or if any external command executed with system(...) or backticks returns error code then exit immediately)