AndreaNobili's questions

I am not a system engineer (I am more a software developer) and I have the following doubt. I have to download an Ubuntu ISO in order to use it on a VCenter instance. Bascailly this will be for a server that will host a server application (it is not intended for desktop user, the connection to this machine will be done only via SSH). It will be used for a production environemtn so I suppose that a nice choise will be adopt an LTS version.

What version do you reccoment do use for a case like this one? I was checking on the Ubuntu website and I suppose that I have to download an Ubuntu Server version (not the desktop one).

So I was thinking to use this one: https://ubuntu.com/download/server

but what is the correct option that I need?

• Option 1: Instant Ubuntu VMs: what is this?
• Option 2: Manual Server Installation: this provide an ISO so I suppose that it could be the right one.
• Option 3: Automated Server Provisioning: what is this?

The guy that will install it only says to me that he need an ISO so I think that the Option 2 is the correct one. But I am not totally sure.

I have installed STS (Spring Tool Suite) IDE on Ubuntu 20.04 and I am finding the following problem with the icon in the launcher.

The problem is that executing this application, it correctly start but the icon is fixed as last element in my launcher left vertical bar:

It is pretty unconfortable. I can't move it another position (as I have done for all the other icons). If I try to drag and drop this icon in another position (between other icons in my launcher bar) it come back to the last position.

I also created an sts.desktop file and I put it into the /home/andrea/.local/share/applications directory, this is its content:

[Desktop Entry]
Type=Application
Name=sts
Comment=Spring Tool Suite
Icon=/home/andrea/DEV-TOOLS/sts-4.11.0.RELEASE/icon.xpm
Exec=/home/andrea/DEV-TOOLS/sts-4.11.0.RELEASE/SpringToolSuite4
Terminal=false
Categories=Development;IDE;Java;
StartupWMClass=STS

After that I created this file if I search "sts" into my application it find it and clicking on the icon it is executed but I still have the same problem: the icon is the last one and I can't change its position

I am not so into Linux and I am experiencing a very strange problem with a Linux 19.10 system on which I am working into VmWare workstation (but I suppose that it is not a VMware related problem).

The problem is that I had to restart the system due to a crash that freeze the system. After the restart I have no more Internet connection.

Performing the ifconfig command into the shell I obtain:

developer@developer-virtual-machine:/etc/network$ ifconfig
lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Loopback locale)
        RX packets 2508  bytes 186240 (186.2 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 2508  bytes 186240 (186.2 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

So it seems that for some reason it loose the ethernet interface used by VmWare to connect in NAT mode.

I tried to restart the system (also the host Windows machine on which VMWare is installed) but I still have this problem. How can I try to fix it?

EDIT-1: Performing sudo lshw -C network I obtain this output:

developer@developer-virtual-machine:~$ sudo lshw -C network
[sudo] password di developer: 
  *-network DISABLED        
       description: Ethernet interface
       product: 82545EM Gigabit Ethernet Controller (Copper)
       vendor: Intel Corporation
       physical id: 1
       bus info: pci@0000:02:01.0
       logical name: ens33
       version: 01
       serial: 00:50:56:3a:4b:1e
       size: 1Gbit/s
       capacity: 1Gbit/s
       width: 64 bits
       clock: 66MHz
       capabilities: pm pcix bus_master cap_list rom ethernet physical logical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=e1000 driverversion=7.3.21-k8-NAPI duplex=full latency=0 link=no mingnt=255 multicast=yes port=twisted pair speed=1Gbit/s
       resources: irq:19 memory:fd5c0000-fd5dffff memory:fdff0000-fdffffff ioport:2000(size=64) memory:fd500000-fd50ffff

It seems that the networking is disabled

I am not so into Linux and I have the following problem

I have an Ubuntu 18.04 VM that is in the network of a client that is unable to perform ping.

I have tried to perform:

ping 8.8.8.8

I discovered that I can ping another machine in the same network but I can't ping adresses on Internet (outside the network)

but I am obtaining no response.

What could be the problem? How to investigate and try to fix it?

I am not so into Linux. On an Ubuntu VM on a client environment it seems that I can't use apt-get command.

In particular trying to perform:

sudo apt-get install ntpdate

I am obtain this message error:

Temporary failure resolving 'archive.ubuntu.com'

Here a screenshot:

What could be the cause of the error? Can something block apt-get on this infrastructure? (firewall or something like this?)

Altro trying to perform a:

sudo apt-get update

I have the same problem

I tried also to install other application via apt-get and I am facing the same issue? In case there are other solution to manually download and install ntpdate without using apt-get?

I am not so into Linux and I have the following doubts: a client provided me an Ubuntu 18.04.3 LTS virtual machine which I access via SSH. (I am using MobaxTerm as SSH client but it should not be the problem.) The shell used is sh.

The problem is that in the shell the autocomplete function is not working as I expected using the Tab key.

It simply put the classical tab white spaces.

Why? How can I change this configuration?

I am absolute not into Linux system administration (I am a software developer) and I have the following question for you about services.

On an Ubuntu 18.04.2 LTS machine there is installed a software as service. I mean that I can run it performing this statment in the shell:

sudo service wso2ei start

and I have the service configuration file into:

/etc/systemd/system/wso2ei.service

that contains something like this:

[Unit]
Description=WSO2EI

After=syslog.target
After=network.target

[Service]
Type=simple
WorkingDirectory=/usr/lib/wso2/wso2ei/6.4.0
User=root
Group=nogroup
Environment=JAVA_HOME=/usr/lib/wso2/wso2ei/6.4.0/jdk/jdk1.8.0_192
Environment=CARBON_HOME=/usr/lib/wso2/wso2ei/6.4.0

StandardOutput=syslog
StandardError=syslog

ExecStart=/usr/lib/wso2/wso2ei/6.4.0/bin/integrator.sh
ExecStop=/usr/lib/wso2/wso2ei/6.4.0/integrator.sh stop

#TimeoutSec=130

[Install]
WantedBy=multi-user.target

it is working fine and I can start and stop the service by the following statments:

sudo service wso2ei start

and

sudo service wso2ei stopt

So this service is working fine...but...I tried to list all the services by this stament:

service --status-all

I expected to find my wso2ei service into the output list but there isn't !!!

This is my output:

$ sudo service --status-all
 [ - ]  acpid
 [ + ]  apparmor
 [ + ]  apport
 [ + ]  atd
 [ + ]  cntlm
 [ - ]  console-setup.sh
 [ + ]  cron
 [ - ]  cryptdisks
 [ - ]  cryptdisks-early
 [ + ]  dbus
 [ + ]  ebtables
 [ + ]  grub-common
 [ - ]  hwclock.sh
 [ + ]  irqbalance
 [ + ]  iscsid
 [ - ]  keyboard-setup.sh
 [ + ]  kmod
 [ - ]  lvm2
 [ + ]  lvm2-lvmetad
 [ + ]  lvm2-lvmpolld
 [ + ]  lxcfs
 [ - ]  lxd
 [ - ]  mdadm
 [ - ]  mdadm-waitidle
 [ - ]  ntp
 [ - ]  open-iscsi
 [ - ]  open-vm-tools
 [ - ]  plymouth
 [ - ]  plymouth-log
 [ + ]  procps
 [ - ]  rsync
 [ + ]  rsyslog
 [ - ]  screen-cleanup
 [ + ]  ssh
 [ + ]  udev
 [ - ]  ufw
 [ + ]  unattended-upgrades
 [ - ]  uuidd
$

Why my wso2ei is not in this list? What is wrong? What am I missing?

Moreover: if I check the status of this particular service I obtain this output:

$ sudo service wso2ei status
● wso2ei.service - WSO2EI
   Loaded: loaded (/etc/systemd/system/wso2ei.service; enabled; vendor preset: enabled)
   Active: active (running) since Fri 2019-10-11 21:03:06 CEST; 1 day 22h ago
  Process: 56854 ExecStop=/usr/lib/wso2/wso2ei/6.4.0/integrator.sh stop (code=exited, status=203/EXEC)
 Main PID: 56912 (integrator.sh)
    Tasks: 179 (limit: 9486)
   CGroup: /system.slice/wso2ei.service
           ├─56912 /bin/sh /usr/lib/wso2/wso2ei/6.4.0/bin/integrator.sh
           └─56958 /usr/lib/wso2/wso2ei/6.4.0/jdk/jdk1.8.0_192/bin/java -Xbootclasspath/a: -Xms256m -Xmx1024m -XX:+HeapDumpOnOutOfMemoryError -X

So I think that the service statment find the wso2ei service in some way.

I think that I am missing something...

I am not so into Linux and I have the following problem. I am working on n Ubuntu 16.04 system.

In this system I have a program that it is started from the command line in this way:

service wso2ei start 

and stopped by:

service wso2ei stop

I think that somewhere it should be defined as a service or something like this. What exactly is this? And where is it defined these statment? (I think that is should be defined the association between the start command and the executable file that have to be executed)

I am not so into Linux and I have the following problem related to the fact that my /boot partition seems to be full and it seems to cause a problem trying to install a program.

I try to explain in detail my doubts because I am not so into system engineering (I am a software developer).

1) Performing the lsblk statment lists information about all available or the specified block devices.

Empirically I think that it should show the list of all the partitions/mounted disks or something like this. What exactly means with the terms block devices?

So if I perform this statment on my Ubuntu system I obtain:

root@MyServer-VPS:~# lsblk
NAME           MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
fd0              2:0    1    4K  0 disk
sda              8:0    0   20G  0 disk
├─sda1           8:1    0  476M  0 part /boot
├─sda2           8:2    0    1K  0 part
├─sda3           8:3    0   10G  0 part
│ └─vg-lv_root 252:0    0 18.6G  0 lvm  /
└─sda5           8:5    0  9.5G  0 part
  ├─vg-lv_root 252:0    0 18.6G  0 lvm  /
  └─vg-lv_swap 252:1    0  952M  0 lvm  [SWAP]
sr0             11:0    1 1024M  0 rom

So what is the difference between disk, part (it should be a partition of the parent disk), lvm and rom?

A specific partition is boot, this one:

sda1           8:1    0  476M  0 part /boot

that is a sda disk partition.

From what I know it should contains the Linux Kernel downloaded versions. Is it?

Ok, the mount point is /boot so I think that it is the /boot directory into my system (is it?), this is the content:

root@MyServer-VPS:/boot# ls
abi-4.4.0-21-generic  config-4.4.0-21-generic  grub                         System.map-4.4.0-21-generic  vmlinuz-4.4.0-21-generic
abi-4.4.0-31-generic  config-4.4.0-31-generic  initrd.img-4.4.0-21-generic  System.map-4.4.0-31-generic  vmlinuz-4.4.0-31-generic
abi-4.4.0-34-generic  config-4.4.0-34-generic  initrd.img-4.4.0-31-generic  System.map-4.4.0-34-generic  vmlinuz-4.4.0-34-generic
abi-4.4.0-38-generic  config-4.4.0-38-generic  initrd.img-4.4.0-34-generic  System.map-4.4.0-38-generic  vmlinuz-4.4.0-38-generic
abi-4.4.0-42-generic  config-4.4.0-42-generic  initrd.img-4.4.0-38-generic  System.map-4.4.0-42-generic  vmlinuz-4.4.0-42-generic
abi-4.4.0-45-generic  config-4.4.0-45-generic  initrd.img-4.4.0-42-generic  System.map-4.4.0-45-generic  vmlinuz-4.4.0-45-generic
abi-4.4.0-47-generic  config-4.4.0-47-generic  initrd.img-4.4.0-45-generic  System.map-4.4.0-47-generic  vmlinuz-4.4.0-47-generic
abi-4.4.0-51-generic  config-4.4.0-51-generic  initrd.img-4.4.0-47-generic  System.map-4.4.0-51-generic  vmlinuz-4.4.0-51-generic
abi-4.4.0-53-generic  config-4.4.0-53-generic  initrd.img-4.4.0-51-generic  System.map-4.4.0-53-generic  vmlinuz-4.4.0-53-generic
abi-4.4.0-57-generic  config-4.4.0-57-generic  initrd.img-4.4.0-53-generic  System.map-4.4.0-57-generic  vmlinuz-4.4.0-57-generic
abi-4.4.0-59-generic  config-4.4.0-59-generic  lost+found                   System.map-4.4.0-59-generic  vmlinuz-4.4.0-59-generic

So what these contents exactly represents? Are the differents Linux kernel versions downloaded on this system?

What are the difference between the abi-, config-, initrd.img-, System.map- and vmlinuz-4 files?

How can I detect the used kernel version?

2) Performing the df -h statment I obtain this output:

root@MyServer-VPS:~# df -h
Filesystem              Size  Used Avail Use% Mounted on
udev                    477M     0  477M   0% /dev
tmpfs                   100M   16M   84M  16% /run
/dev/mapper/vg-lv_root   19G   12G  6.3G  64% /
tmpfs                   497M     0  497M   0% /dev/shm
tmpfs                   5.0M     0  5.0M   0% /run/lock
tmpfs                   497M     0  497M   0% /sys/fs/cgroup
/dev/sda1               461M  458M     0 100% /boot
tmpfs                   100M     0  100M   0% /run/user/0

In particular I have that:

/dev/sda1               461M  458M     0 100% /boot

So it means that my /boot partition is completly full?

My problem is: can I saftly deetect delete all the old kernel version (the not used one) to free up space in the /boot ?

How can I do it?

I am not so into Linux and I have the following problem.

I have to change user (using a given user) on a Linux server.

So I use the

[myusername@myserver~]$ sudo -i -u otherusername
[sudo] password for myusername:
myusername is not in the sudoers file.  This incident will be reported.
[myusername@myserver~]$

So it seems that I have not permission to do it or something like this. What extactly is the problem?

I am not a Ruby developer and I am finding many difficult to install Redmine (that is developed in Ruby) on an Ububuntu 16.04 server.

I am following this official tutorial: http://www.redmine.org/projects/redmine/wiki/HowTo_Install_Redmine_on_Ubuntu_step_by_step

It seems very simple but I am finding many difficult when it "ensure that the bundler GEM is installed".

I am not sure about what exactly is this bundler GEM that have to be installed. From what I have understand (correct me if I am doing wrong assertion) a GEM is something that packages excutable Ruby application (something like a JAR file in Java).

So, the problem is that when I perform this statment in the bash console:

sudo gem update

I obtain many error messages like this:

root@Betrivius-VPS:~# sudo gem update
Updating installed gems
Updating molinillo
Fetching: molinillo-0.5.4.gem (100%)
Successfully installed molinillo-0.5.4
Parsing documentation for molinillo-0.5.4
Installing ri documentation for molinillo-0.5.4
Installing darkfish documentation for molinillo-0.5.4
Done installing documentation for molinillo after 1 seconds
Parsing documentation for molinillo-0.5.4
Done installing documentation for molinillo after 0 seconds
Updating mysql2
Building native extensions.  This could take a while...
ERROR:  Error installing mysql2:
        ERROR: Failed to build gem native extension.

    current directory: /var/lib/gems/2.3.0/gems/mysql2-0.4.5/ext/mysql2
/usr/bin/ruby2.3 -r ./siteconf20161115-29205-1v41srl.rb extconf.rb
checking for rb_absint_size()... yes
checking for rb_absint_singlebit_p()... yes
checking for ruby/thread.h... yes
checking for rb_thread_call_without_gvl() in ruby/thread.h... yes
checking for rb_thread_blocking_region()... no
checking for rb_wait_for_single_fd()... yes
checking for rb_hash_dup()... yes
checking for rb_intern3()... yes
checking for rb_big_cmp()... yes
checking for mysql_query() in -lmysqlclient... no
-----
mysql client is missing. You may need to 'apt-get install libmysqlclient-dev' or 'yum install mysql-devel', and try again.
-----
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
        --with-opt-dir
        --without-opt-dir
        --with-opt-include
        --without-opt-include=${opt-dir}/include
        --with-opt-lib
        --without-opt-lib=${opt-dir}/lib
        --with-make-prog
        --without-make-prog
        --srcdir=.
        --curdir
        --ruby=/usr/bin/$(RUBY_BASE_NAME)2.3
        --with-mysql-dir
        --without-mysql-dir
        --with-mysql-include
        --without-mysql-include=${mysql-dir}/include
        --with-mysql-lib
        --without-mysql-lib=${mysql-dir}/lib
        --with-mysql-config
        --without-mysql-config
        --with-mysql-dir
        --without-mysql-dir
        --with-mysql-include
        --without-mysql-include=${mysql-dir}/include
        --with-mysql-lib
        --without-mysql-lib=${mysql-dir}/lib
        --with-mysqlclientlib
        --without-mysqlclientlib

To see why this extension failed to compile, please check the mkmf.log which can be found here:

  /var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/mysql2-0.4.5/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in /var/lib/gems/2.3.0/gems/mysql2-0.4.5 for inspection.
Results logged to /var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/mysql2-0.4.5/gem_make.out
Updating nokogiri
Building native extensions.  This could take a while...
ERROR:  Error installing nokogiri:
        ERROR: Failed to build gem native extension.

    current directory: /var/lib/gems/2.3.0/gems/nokogiri-1.6.8.1/ext/nokogiri
/usr/bin/ruby2.3 -r ./siteconf20161115-29205-11qd2.rb extconf.rb
checking if the C compiler accepts ... yes
Building nokogiri using packaged libraries.
Using mini_portile version 2.1.0
checking for gzdopen() in -lz... no
zlib is missing; necessary for building libxml2
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
        --with-opt-dir
        --without-opt-dir
        --with-opt-include
        --without-opt-include=${opt-dir}/include
        --with-opt-lib
        --without-opt-lib=${opt-dir}/lib
        --with-make-prog
        --without-make-prog
        --srcdir=.
        --curdir
        --ruby=/usr/bin/$(RUBY_BASE_NAME)2.3
        --help
        --clean
        --use-system-libraries
        --enable-static
        --disable-static
        --with-zlib-dir
        --without-zlib-dir
        --with-zlib-include
        --without-zlib-include=${zlib-dir}/include
        --with-zlib-lib
        --without-zlib-lib=${zlib-dir}/lib
        --enable-cross-build
        --disable-cross-build

To see why this extension failed to compile, please check the mkmf.log which can be found here:

  /var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/nokogiri-1.6.8.1/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in /var/lib/gems/2.3.0/gems/nokogiri-1.6.8.1 for inspection.
Results logged to /var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/nokogiri-1.6.8.1/gem_make.out
Updating psych
Fetching: psych-2.2.0.gem (100%)
Building native extensions.  This could take a while...
Successfully installed psych-2.2.0
Parsing documentation for psych-2.2.0
Installing ri documentation for psych-2.2.0
Installing darkfish documentation for psych-2.2.0
Done installing documentation for psych after 2 seconds
Parsing documentation for psych-2.2.0
Done installing documentation for psych after 1 seconds
Updating rmagick
Building native extensions.  This could take a while...
ERROR:  Error installing rmagick:
        ERROR: Failed to build gem native extension.

    current directory: /var/lib/gems/2.3.0/gems/rmagick-2.16.0/ext/RMagick
/usr/bin/ruby2.3 -r ./siteconf20161115-29205-1qfeji3.rb extconf.rb
checking for gcc... yes
checking for Magick-config... no
checking for pkg-config... no
Can't install RMagick 2.16.0. Can't find Magick-config or pkg-config in /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin

*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
        --with-opt-dir
        --without-opt-dir
        --with-opt-include
        --without-opt-include=${opt-dir}/include
        --with-opt-lib
        --without-opt-lib=${opt-dir}/lib
        --with-make-prog
        --without-make-prog
        --srcdir=.
        --curdir
        --ruby=/usr/bin/$(RUBY_BASE_NAME)2.3

To see why this extension failed to compile, please check the mkmf.log which can be found here:

  /var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/rmagick-2.16.0/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in /var/lib/gems/2.3.0/gems/rmagick-2.16.0 for inspection.
Results logged to /var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/rmagick-2.16.0/gem_make.out
Updating sqlite3
Building native extensions.  This could take a while...
ERROR:  Error installing sqlite3:
        ERROR: Failed to build gem native extension.

    current directory: /var/lib/gems/2.3.0/gems/sqlite3-1.3.12/ext/sqlite3
/usr/bin/ruby2.3 -r ./siteconf20161115-29205-1mvfxcm.rb extconf.rb
checking for sqlite3.h... no
sqlite3.h is missing. Try 'brew install sqlite3',
'yum install sqlite-devel' or 'apt-get install libsqlite3-dev'
and check your shared library search path (the
location where your sqlite3 shared library is located).
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
        --with-opt-dir
        --without-opt-dir
        --with-opt-include
        --without-opt-include=${opt-dir}/include
        --with-opt-lib
        --without-opt-lib=${opt-dir}/lib
        --with-make-prog
        --without-make-prog
        --srcdir=.
        --curdir
        --ruby=/usr/bin/$(RUBY_BASE_NAME)2.3
        --with-sqlite3-config
        --without-sqlite3-config
        --with-pkg-config
        --without-pkg-config
        --with-sqlite3-dir
        --without-sqlite3-dir
        --with-sqlite3-include
        --without-sqlite3-include=${sqlite3-dir}/include
        --with-sqlite3-lib
        --without-sqlite3-lib=${sqlite3-dir}/lib

To see why this extension failed to compile, please check the mkmf.log which can be found here:

  /var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/sqlite3-1.3.12/mkmf.log

extconf failed, exit code 1

In these error messages it say that I have to check the /var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/sqlite3-1.3.12/mkmf.log file content, this is its content (that maybe could give some additional information to understand where is the probem):

package configuration for sqlite3 is not found
find_header: checking for sqlite3.h... -------------------- no

"gcc -o conftest -I/usr/include/x86_64-linux-gnu/ruby-2.3.0 -I/usr/include/ruby-2.3.0/ruby/backward -I/usr/include/ruby-2.3.0 -I. -Wdate-t$
checked program was:
/* begin */
1: #include "ruby.h"
2:
3: int main(int argc, char **argv)
4: {
5:   return 0;
6: }
/* end */

"gcc -E -I/usr/include/x86_64-linux-gnu/ruby-2.3.0 -I/usr/include/ruby-2.3.0/ruby/backward -I/usr/include/ruby-2.3.0 -I. -Wdate-time -D_FO$
conftest.c:3:21: fatal error: sqlite3.h: No such file or directory
compilation terminated.
checked program was:
/* begin */
1: #include "ruby.h"
2:
3: #include <sqlite3.h>
/* end */

--------------------

So, reading the previous log file, it seems that the problem could be related to:

  fatal error: sqlite3.h: No such file or directory

It seems that a C header file is missing but I really don't know why.

Why I have this problem? What am I missing? How can I try to fix this issue?

Tnx

I am not so into Linux and I have the following doubt following a tutorial.

I have to modify the bashrc file. What kind of settings are contained in this file? I think something related the bash shell environment but I am not so sure about it.

I have to insert this line:

export PATH=$HOME/.local/bin:$HOME/.local/usr/bin:$PATH

What exactly does this line?

I think that export statement is used to create a new variable making it available for other program.

But what exactly does this line? Is PATH the name of the variable that I am defining? What is $HOME?

What means the : symbol between PATH=$HOME/.local/bin and $HOME/.local/usr/bin and $PATH section in the previous expression?

What exactly does this expression mean?

I am not yet a Linux guy and I have the following problem with environment variable.

So I want to add a permanent environment variable and I do in this way:

I open the /etc/profile file and I add this line at the end of this file:

CATALINA_HOME=/opt/apache-tomcat-8.0.24

Where /opt/apache-tomcat-8.0.24 is the folder that contain the tomcat installation (it contains the bin TomCat subfolder)

Then I save this file.

So I close the shell and I reopen it and I try to do:

andrea@andrea-virtual-machine:/$ sudo ./startup.sh
sudo: ./startup.sh: command not found

To start the server instead enter into /opt/apache-tomcat-8.0.24/bin/ and perform the command.

But as you can see I obtain an error. What am I missing?

I have installed 2 development tools named maven and ant using this command:

sudo apt-get install maven ant

How can I discover what are the installation directories for these tools on my system?

I am not yet a Linux guy and I have some problem trying to add a new permanent environment variable.

So I have to set a new environment variable named CATALINA_HOME with this value: /opt/apache-tomcat-8.0.23

What can I do to set it permanently?

Tnx

I am following this tutorial to correctly execute Aptana Studio on my Ubuntu 14.04:

• Command menu in aptana studio 3 is not working in ubuntu 14.04

So I have installed the Oracle JRE and finnally I have create this run.sh file that have to execute Aptana:

!/bin/bash

export UBUNTU_MENUPROXY=0 /home/andrea/Programmi/Aptana_Studio_3/AptanaStudio3

The problem is that when I try to execute this script with my shell I obtain the following error message:

andrea@andrea-virtual-machine:~/Programmi/Aptana_Studio_3$ sudo sh run.sh
run.sh: 1: run.sh: !/bin/bash: not found
run.sh: 3: export: /home/andrea/Programmi/Aptana_Studio_3/AptanaStudio3: bad variable name

Why? What am I missing? How can I fix this issue?

I have the following doubt. In a tutorial related to a software installation that I am following say that I have to execute the following commands (I am doing it into an ssh shell, so this list of steps end with the exit command):

sudo -s
apt-get update
apt-get install -y build-essential libtool libcurl4-openssl-dev libncurses5-dev libudev-dev autoconf automake screen
exit

My doubts are:

What exactly does the -s parameter do after sudo command?

Searching on the web I found that:

‑s [command] The ‑s (shell) option runs the shell specified by the SHELL environment variable if it is set or the shell as specified in the password database. If a command is specified, it is passed to the shell for execution via the shell's ‑c option. If no command is specified, an interactive shell is executed

It seems to me that the sudo -s execute a command using the environment variable of the shell.

But this is not clear for me: in this case what is the command executed with the environment variable? (it only executes sudo -s and not sudo -s [command]).

I have two directories that should contain the same files and have the same directory structure.

I think that something is missing in one of these directories.

Using the bash shell, is there a way to compare my directories and see if one of them is missing files that are present in the other?

I am working on this pre-existent .desktop file and I have a doubt:

The file content is:

[Desktop Entry]
#Icon=connect-data-space
Icon=XCloud
Categories=Utility;
Type=Application
#Exec=/usr/share/ConnectDataSpace/appl/launcher.sh
Exec=/usr/share/XCloud/appl/launcher.sh
Name[en_US]=Connect Data Space
#Name=Connect Data Space
Name=XCloud
Comment[en_US]=
Comment=
StartupNotify=true
Terminal=false
OnlyShowIn=GNOME;Unity;
StartupWMClass=ConnectDataSpace
Actions=CheckUpgrade

[Desktop Action CheckUpgrade]
Name=Verifica Aggiornamenti
#Exec=java -jar /usr/share/ConnectDataSpace/appl/lib/shellExtBridge.jar -checkupgrade
Exec=java -jar /usr/share/XCloud/appl/lib/shellExtBridge.jar -checkupgrade
OnlyShowIn=GNOME;Unity;

What exactly does the StartupWMClass field of this file represent?

I am a Linux Ubuntu user and I have some problem setting the proxy on my entire system.

I go into the network settings of my Gnome and then I go to the Network Proxy settings mask and then I put my proxy for the HTTP Proxy* as Manual, then I click on the Applies to the entire system button, it ask me my password and it is finish

The problem is that if I open a shell, the network don't work and I can't ping anyting, infact I obtain only:

andrea@andrea-Studio-1555:~$ ping google.com
PING google.com (173.194.35.7) 56(84) bytes of data.

and the cursor still blink and don't go on...

Why? What can I do to go out with my proxy in the shell?