问题描述
今天在学习时，出现如下报错：（使用的是Ubuntu 20.04.5 LTS）
lucky@DESKTOP-VQ8KID4:~$ sudo apt install rs
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package rs
报错截图：
错误原因：出现无法定位软件包原因是因为ubuntu不同的版本对应ROS不同的版本。
解决方案
- 提示找不到软件包，首先判断是否是主机正常联网。方法：可以通过
ping www.baidu.com检测。如下图所示：
lucky@DESKTOP-VQ8KID4:~$ ping baidu.com
PING baidu.com (110.242.68.66) 56(84) bytes of data.
64 bytes from 110.242.68.66 (110.242.68.66): icmp_seq=1 ttl=45 time=34.9 ms
64 bytes from 110.242.68.66 (110.242.68.66): icmp_seq=2 ttl=45 time=37.3 ms
64 bytes from 110.242.68.66 (110.242.68.66): icmp_seq=3 ttl=45 time=36.8 ms
^C
--- baidu.com ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2270ms
rtt min/avg/max/mdev = 34.925/36.355/37.335/1.034 ms
如果连不上网，想办法连上网。
- 其次，这个问题是改变了“下载源”，没有更新的原因，在命令窗口执行如下命令：
lucky@DESKTOP-VQ8KID4:~$ sudo apt-get update
Hit:1 http://archive.ubuntu.com/ubuntu focal InRelease
Get:2 http://archive.ubuntu.com/ubuntu focal-updates InRelease [114 kB]
Get:3 http://security.ubuntu.com/ubuntu focal-security InRelease [114 kB]
Get:4 http://archive.ubuntu.com/ubuntu focal-backports InRelease [108 kB]
Get:5 http://archive.ubuntu.com/ubuntu focal/universe amd64 Packages [8628 kB]
Get:6 http://security.ubuntu.com/ubuntu focal-security/main amd64 Packages [1752 kB]
Get:7 http://security.ubuntu.com/ubuntu focal-security/main Translation-en [293 kB]
Get:8 http://archive.ubuntu.com/ubuntu focal/universe Translation-en [5124 kB]
Get:9 http://security.ubuntu.com/ubuntu focal-security/main amd64 c-n-f Metadata [11.1 kB]
Get:10 http://security.ubuntu.com/ubuntu focal-security/restricted amd64 Packages [1212 kB]
Get:11 http://archive.ubuntu.com/ubuntu focal/universe amd64 c-n-f Metadata [265 kB]
Get:12 http://archive.ubuntu.com/ubuntu focal/multiverse amd64 Packages [144 kB]
Get:13 http://archive.ubuntu.com/ubuntu focal/multiverse Translation-en [104 kB]
Get:14 http://archive.ubuntu.com/ubuntu focal/multiverse amd64 c-n-f Metadata [9136 B]
Get:15 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 Packages [2129 kB]
Get:16 http://security.ubuntu.com/ubuntu focal-security/restricted Translation-en [172 kB]
Get:17 http://security.ubuntu.com/ubuntu focal-security/universe amd64 Packages [735 kB]
Get:18 http://archive.ubuntu.com/ubuntu focal-updates/main Translation-en [376 kB]
Get:19 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 c-n-f Metadata [16.0 kB]
Get:20 http://archive.ubuntu.com/ubuntu focal-updates/restricted amd64 Packages [1301 kB]
Get:21 http://archive.ubuntu.com/ubuntu focal-updates/restricted Translation-en [185 kB]
Get:22 http://archive.ubuntu.com/ubuntu focal-updates/universe amd64 Packages [964 kB]
Get:23 http://security.ubuntu.com/ubuntu focal-security/universe Translation-en [135 kB]
Get:24 http://security.ubuntu.com/ubuntu focal-security/universe amd64 c-n-f Metadata [15.2 kB]
Get:25 http://archive.ubuntu.com/ubuntu focal-updates/universe Translation-en [220 kB]
Get:26 http://security.ubuntu.com/ubuntu focal-security/multiverse amd64 Packages [22.2 kB]
Get:27 http://archive.ubuntu.com/ubuntu focal-updates/universe amd64 c-n-f Metadata [21.6 kB]
Get:28 http://security.ubuntu.com/ubuntu focal-security/multiverse Translation-en [5376 B]
Get:29 http://archive.ubuntu.com/ubuntu focal-updates/multiverse amd64 Packages [24.4 kB]
Get:30 http://security.ubuntu.com/ubuntu focal-security/multiverse amd64 c-n-f Metadata [508 B]
Get:31 http://archive.ubuntu.com/ubuntu focal-updates/multiverse Translation-en [7316 B]
Get:32 http://archive.ubuntu.com/ubuntu focal-updates/multiverse amd64 c-n-f Metadata [588 B]
Get:33 http://archive.ubuntu.com/ubuntu focal-backports/main amd64 Packages [45.6 kB]
Get:34 http://archive.ubuntu.com/ubuntu focal-backports/main Translation-en [16.3 kB]
Get:35 http://archive.ubuntu.com/ubuntu focal-backports/main amd64 c-n-f Metadata [1420 B]
Get:36 http://archive.ubuntu.com/ubuntu focal-backports/restricted amd64 c-n-f Metadata [116 B]
Get:37 http://archive.ubuntu.com/ubuntu focal-backports/universe amd64 Packages [23.9 kB]
Get:38 http://archive.ubuntu.com/ubuntu focal-backports/universe Translation-en [16.0 kB]
Get:39 http://archive.ubuntu.com/ubuntu focal-backports/universe amd64 c-n-f MetBuilding dependency tree
Reading state information... Done
The following NEW packages will be installed:
rs
0 upgraded, 1 newly installed, 0 to remove and 29 not upgraded.
Need to get 15.6 kB of archives.
After this operation, 43.0 kB of additional disk space will be used.
Get:1 http://archive.ubuntu.com/ubuntu focal/universe amd64 rs amd64 20200313-1 [15.6 kB]
Fetched 15.6 kB in 1s (20.5 kB/s)
Selecting previously unselected package rs.
(Reading database ... 32563 files and directories currently installed.)
Preparing to unpack .../rs_20200313-1_amd64.deb ...
Unpacking rs (20200313-1) ...
Setting up rs (20200313-1) ...
Processing triggers for man-db (2.9.1-1) ...
问题解决！这时可以正常安装了：
lucky@DESKTOP-VQ8KID4:~$ sudo apt install reminiscence
Reading package lists... Done
Selecting previously unselected package libcaca0:amd64.
(Reading database ... 32614 files and directories currently installed.)
Preparing to unpack .../libcaca0_0.99.beta19-2.1ubuntu1.20.04.2_amd64.deb ...
Unpacking libcaca0:amd64 (0.99.beta19-2.1ubuntu1.20.04.2) ...
Selecting previously unselected package libsdl1.2debian:amd64.
Preparing to unpack .../libsdl1.2debian_1.2.15+dfsg2-5_amd64.deb ...
Unpacking libsdl1.2debian:amd64 (1.2.15+dfsg2-5) ...
Selecting previously unselected package reminiscence.
Preparing to unpack .../reminiscence_0.2.1-2build2_amd64.deb ...
Unpacking reminiscence (0.2.1-2build2) ...
Setting up libcaca0:amd64 (0.99.beta19-2.1ubuntu1.20.04.2) ...
Setting up libsdl1.2debian:amd64 (1.2.15+dfsg2-5) ...
Setting up reminiscence (0.2.1-2build2) ...
Processing triggers for libc-bin (2.31-0ubuntu9.9) ...
Processing triggers for man-db (2.9.1-1) ...
Processing triggers for mime-support (3.64ubuntu1) ...
扩展
最后，扩展一些东西：
在Linux下，每个Linux的发行版，比如我的版本是Ubuntu 16.04 64位 ，都会维护一个自己的软件仓库，我们常用的几乎所有软件都在这里面。在Ubuntu下，我们维护一个源列表，源列表里面都是一些网址信息，这每一条网址就是一个源，这个地址指向的数据标识着这台源服务器上有哪些软件可以安装使用。
编辑源列表命令：
sudo gedit /etc/apt/sources.list
在这个文件里加入或者注释（加#）掉一些源后。我们的源列表里指向的软件就会增加或减少一部分。就需要手动更新一下。就是sudo apt-get update命令。这个命令，会访问源列表里的每个网址，并读取软件列表，然后保存在本地电脑。
在sudo apt-get update之后通常会使用如下命令同步源列表，去真正地更新软件。
lucky@DESKTOP-VQ8KID4:~$ sudo apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following packages will be upgraded:
bind9-dnsutils bind9-host bind9-libs curl isc-dhcp-client isc-dhcp-common
libcurl3-gnutls libcurl4 libnss-systemd libpam-systemd libpcre2-8-0
libsqlite3-0 libsystemd0 libtss2-esys0 libudev1 libwayland-client0 sosreport
systemd systemd-sysv systemd-timesyncd tzdata ubuntu-advantage-tools udev
vim vim-common vim-runtime vim-tiny xxd zlib1g
29 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
18 standard security updates
Need to get 17.7 MB of archives.
After this operation, 91.1 kB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 udev amd64 245.4-4ubuntu3.18 [1367 kB]
Get:2 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 libudev1 amd64 245.4-4ubuntu3.18 [76.3 kB]
Get:3 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 systemd-sysv amd64 245.4-4ubuntu3.18 [10.3 kB]
Get:4 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 systemd-timesyncd amd64 245.4-4ubuntu3.18 [28.1 kB]
Get:5 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 libnss-systemd amd64 245.4-4ubuntu3.18 [96.1 kB]
Get:6 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 libpam-systemd amd64 245.4-4ubuntu3.18 [186 kB]
Get:7 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 libpcre2-8-0 amd64 10.34-7ubuntu0.1 [198 kB]
Get:8 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 systemd amd64 245.4-4ubuntu3.18 [3808 kB]
Get:9 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 libsystemd0 amd64 245.4-4ubuntu3.18 [269 kB]
Get:10 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 zlib1g amd64 1:1.2.11.dfsg-2ubuntu1.4 [53.9 kB]
Get:11 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 isc-dhcp-client amd64 4.4.1-2.1ubuntu5.20.04.4 [247 kB]
Get:12 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 isc-dhcp-common amd64 4.4.1-2.1ubuntu5.20.04.4 [45.0 kB]
Get:13 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 libsqlite3-0 amd64 3.31.1-4ubuntu0.4 [549 kB]
Get:14 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 tzdata all 2022c-0ubuntu0.20.04.0 [288 kB]
Get:15 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 ubuntu-advantage-tools amd64 27.11.2~20.04.1 [160 kB]
Get:16 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 xxd amd64 2:8.1.2269-1ubuntu5.9 [50.0 kB]
Get:17 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 vim amd64 2:8.1.2269-1ubuntu5.9 [1238 kB]
Get:18 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 vim-tiny amd64 2:8.1.2269-1ubuntu5.9 [578 kB]
Get:19 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 vim-runtime all 2:8.1.2269-1ubuntu5.9 [5873 kB]
Get:20 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 vim-common all 2:8.1.2269-1ubuntu5.9 [85.0 kB]
Get:21 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 bind9-dnsutils amd64 1:9.16.1-0ubuntu2.11 [134 kB]
Get:22 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 bind9-libs amd64 1:9.16.1-0ubuntu2.11 [1108 kB]
Get:23 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 bind9-host amd64 1:9.16.1-0ubuntu2.11 [43.0 kB]
Get:24 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 curl amd64 7.68.0-1ubuntu2.13 [161 kB]
Get:25 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 libcurl4 amd64 7.68.0-1ubuntu2.13 [235 kB]
Get:26 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 libcurl3-gnutls amd64 7.68.0-1ubuntu2.13 [233 kB]
Get:27 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 libtss2-esys0 amd64 2.3.2-1ubuntu0.20.04.1 [226 kB]
Get:28 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 libwayland-client0 amd64 1.18.0-1ubuntu0.1 [23.9 kB]
Get:29 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 sosreport amd64 4.3-1ubuntu0.20.04.2 [294 kB]
Fetched 17.7 MB in 12s (1498 kB/s)
Preconfiguring packages ...
(Reading database ... 32569 files and directories currently installed.)
Preparing to unpack .../udev_245.4-4ubuntu3.18_amd64.deb ...
Unpacking udev (245.4-4ubuntu3.18) over (245.4-4ubuntu3.17) ...
Preparing to unpack .../libudev1_245.4-4ubuntu3.18_amd64.deb ...
Unpacking libudev1:amd64 (245.4-4ubuntu3.18) over (245.4-4ubuntu3.17) ...
Setting up libudev1:amd64 (245.4-4ubuntu3.18) ...
(Reading database ... 32569 files and directories currently installed.)
Preparing to unpack .../systemd-sysv_245.4-4ubuntu3.18_amd64.deb ...
Unpacking systemd-sysv (245.4-4ubuntu3.18) over (245.4-4ubuntu3.17) ...
Preparing to unpack .../systemd-timesyncd_245.4-4ubuntu3.18_amd64.deb ...
Unpacking systemd-timesyncd (245.4-4ubuntu3.18) over (245.4-4ubuntu3.17) ...
Preparing to unpack .../libnss-systemd_245.4-4ubuntu3.18_amd64.deb ...
Unpacking libnss-systemd:amd64 (245.4-4ubuntu3.18) over (245.4-4ubuntu3.17) ...
Preparing to unpack .../libpam-systemd_245.4-4ubuntu3.18_amd64.deb ...
Unpacking libpam-systemd:amd64 (245.4-4ubuntu3.18) over (245.4-4ubuntu3.17) ...
Preparing to unpack .../libpcre2-8-0_10.34-7ubuntu0.1_amd64.deb ...
Unpacking libpcre2-8-0:amd64 (10.34-7ubuntu0.1) over (10.34-7) ...
Setting up libpcre2-8-0:amd64 (10.34-7ubuntu0.1) ...
(Reading database ... 32569 files and directories currently installed.)
Preparing to unpack .../systemd_245.4-4ubuntu3.18_amd64.deb ...
Unpacking systemd (245.4-4ubuntu3.18) over (245.4-4ubuntu3.17) ...
Preparing to unpack .../libsystemd0_245.4-4ubuntu3.18_amd64.deb ...
Unpacking libsystemd0:amd64 (245.4-4ubuntu3.18) over (245.4-4ubuntu3.17) ...
Setting up libsystemd0:amd64 (245.4-4ubuntu3.18) ...
(Reading database ... 32569 files and directories currently installed.)
Preparing to unpack .../zlib1g_1%3a1.2.11.dfsg-2ubuntu1.4_amd64.deb ...
Unpacking zlib1g:amd64 (1:1.2.11.dfsg-2ubuntu1.4) over (1:1.2.11.dfsg-2ubuntu1.3) ...
Setting up zlib1g:amd64 (1:1.2.11.dfsg-2ubuntu1.4) ...
(Reading database ... 32569 files and directories currently installed.)
Preparing to unpack .../00-isc-dhcp-client_4.4.1-2.1ubuntu5.20.04.4_amd64.deb ...
Unpacking isc-dhcp-client (4.4.1-2.1ubuntu5.20.04.4) over (4.4.1-2.1ubuntu5.20.04.3) ...
Preparing to unpack .../01-isc-dhcp-common_4.4.1-2.1ubuntu5.20.04.4_amd64.deb ...
Unpacking isc-dhcp-common (4.4.1-2.1ubuntu5.20.04.4) over (4.4.1-2.1ubuntu5.20.04.3) ...
Preparing to unpack .../02-libsqlite3-0_3.31.1-4ubuntu0.4_amd64.deb ...
Unpacking libsqlite3-0:amd64 (3.31.1-4ubuntu0.4) over (3.31.1-4ubuntu0.3) ...
Preparing to unpack .../03-tzdata_2022c-0ubuntu0.20.04.0_all.deb ...
Unpacking tzdata (2022c-0ubuntu0.20.04.0) over (2022a-0ubuntu0.20.04) ...
Preparing to unpack .../04-ubuntu-advantage-tools_27.11.2~20.04.1_amd64.deb ...
Unpacking ubuntu-advantage-tools (27.11.2~20.04.1) over (27.10.1~20.04.1) ...
Preparing to unpack .../05-xxd_2%3a8.1.2269-1ubuntu5.9_amd64.deb ...
Unpacking xxd (2:8.1.2269-1ubuntu5.9) over (2:8.1.2269-1ubuntu5.7) ...
Preparing to unpack .../06-vim_2%3a8.1.2269-1ubuntu5.9_amd64.deb ...
Unpacking vim (2:8.1.2269-1ubuntu5.9) over (2:8.1.2269-1ubuntu5.7) ...
Preparing to unpack .../07-vim-tiny_2%3a8.1.2269-1ubuntu5.9_amd64.deb ...
Unpacking vim-tiny (2:8.1.2269-1ubuntu5.9) over (2:8.1.2269-1ubuntu5.7) ...
Preparing to unpack .../08-vim-runtime_2%3a8.1.2269-1ubuntu5.9_all.deb ...
Unpacking vim-runtime (2:8.1.2269-1ubuntu5.9) over (2:8.1.2269-1ubuntu5.7) ...
Preparing to unpack .../09-vim-common_2%3a8.1.2269-1ubuntu5.9_all.deb ...
Unpacking vim-common (2:8.1.2269-1ubuntu5.9) over (2:8.1.2269-1ubuntu5.7) ...
Preparing to unpack .../10-bind9-dnsutils_1%3a9.16.1-0ubuntu2.11_amd64.deb ...
Unpacking bind9-dnsutils (1:9.16.1-0ubuntu2.11) over (1:9.16.1-0ubuntu2.10) ...
Preparing to unpack .../11-bind9-libs_1%3a9.16.1-0ubuntu2.11_amd64.deb ...
Unpacking bind9-libs:amd64 (1:9.16.1-0ubuntu2.11) over (1:9.16.1-0ubuntu2.10) ...
Preparing to unpack .../12-bind9-host_1%3a9.16.1-0ubuntu2.11_amd64.deb ...
Unpacking bind9-host (1:9.16.1-0ubuntu2.11) over (1:9.16.1-0ubuntu2.10) ...
Preparing to unpack .../13-curl_7.68.0-1ubuntu2.13_amd64.deb ...
Unpacking curl (7.68.0-1ubuntu2.13) over (7.68.0-1ubuntu2.12) ...
Preparing to unpack .../14-libcurl4_7.68.0-1ubuntu2.13_amd64.deb ...
Unpacking libcurl4:amd64 (7.68.0-1ubuntu2.13) over (7.68.0-1ubuntu2.12) ...
Preparing to unpack .../15-libcurl3-gnutls_7.68.0-1ubuntu2.13_amd64.deb ...
Unpacking libcurl3-gnutls:amd64 (7.68.0-1ubuntu2.13) over (7.68.0-1ubuntu2.12) ...
Preparing to unpack .../16-libtss2-esys0_2.3.2-1ubuntu0.20.04.1_amd64.deb ...
Unpacking libtss2-esys0 (2.3.2-1ubuntu0.20.04.1) over (2.3.2-1) ...
Preparing to unpack .../17-libwayland-client0_1.18.0-1ubuntu0.1_amd64.deb ...
Unpacking libwayland-client0:amd64 (1.18.0-1ubuntu0.1) over (1.18.0-1) ...
Preparing to unpack .../18-sosreport_4.3-1ubuntu0.20.04.2_amd64.deb ...
Unpacking sosreport (4.3-1ubuntu0.20.04.2) over (4.3-1ubuntu0.20.04.1) ...
Setting up bind9-libs:amd64 (1:9.16.1-0ubuntu2.11) ...
Setting up libtss2-esys0 (2.3.2-1ubuntu0.20.04.1) ...
Setting up libsqlite3-0:amd64 (3.31.1-4ubuntu0.4) ...
Setting up isc-dhcp-client (4.4.1-2.1ubuntu5.20.04.4) ...
Setting up libcurl3-gnutls:amd64 (7.68.0-1ubuntu2.13) ...
Setting up xxd (2:8.1.2269-1ubuntu5.9) ...
Setting up tzdata (2022c-0ubuntu0.20.04.0) ...
Current default time zone: 'Asia/Shanghai'
Local time is now: Mon Oct 10 10:53:22 CST 2022.
Universal Time is now: Mon Oct 10 02:53:22 UTC 2022.
Run 'dpkg-reconfigure tzdata' if you wish to change it.
Setting up vim-common (2:8.1.2269-1ubuntu5.9) ...
Setting up udev (245.4-4ubuntu3.18) ...
invoke-rc.d: could not determine current runlevel
update-initramfs: deferring update (trigger activated)
Setting up sosreport (4.3-1ubuntu0.20.04.2) ...
Setting up libcurl4:amd64 (7.68.0-1ubuntu2.13) ...
Setting up isc-dhcp-common (4.4.1-2.1ubuntu5.20.04.4) ...
Setting up curl (7.68.0-1ubuntu2.13) ...
Setting up ubuntu-advantage-tools (27.11.2~20.04.1) ...
Installing new version of config file /etc/ubuntu-advantage/help_data.yaml ...
Installing new version of config file /etc/ubuntu-advantage/uaclient.conf ...
Setting up vim-runtime (2:8.1.2269-1ubuntu5.9) ...
Setting up bind9-host (1:9.16.1-0ubuntu2.11) ...
Setting up libwayland-client0:amd64 (1.18.0-1ubuntu0.1) ...
Setting up vim (2:8.1.2269-1ubuntu5.9) ...
Setting up vim-tiny (2:8.1.2269-1ubuntu5.9) ...
Setting up bind9-dnsutils (1:9.16.1-0ubuntu2.11) ...
Setting up systemd (245.4-4ubuntu3.18) ...
Initializing machine ID from random generator.
Setting up systemd-timesyncd (245.4-4ubuntu3.18) ...
Setting up systemd-sysv (245.4-4ubuntu3.18) ...
Setting up libnss-systemd:amd64 (245.4-4ubuntu3.18) ...
Setting up libpam-systemd:amd64 (245.4-4ubuntu3.18) ...
Processing triggers for mime-support (3.64ubuntu1) ...
Processing triggers for libc-bin (2.31-0ubuntu9.9) ...
Processing triggers for man-db (2.9.1-1) ...
Processing triggers for dbus (1.12.16-2ubuntu2.2) ...
Processing triggers for initramfs-tools (0.136ubuntu6.7) ...