Bug#931522: apt: does not provide a means to check whether updates are available from a script

[Svetlana Tkachenko <svetlana@members.fsf.org>]

Package: apt
Version: 1.8.2
Severity: wishlist

Dear Maintainer,

*** Reporter, please consider answering these questions, where appropriate ***

I wanted to check whether or not updates are available from my script written
in bash.

I found that aptitude can tell the number of packages which are available
for upgrade using

 aptitude search '~U' | wc -l

But for apt there is no reliable way to do the same, it outputs a warning that
its output is not meant to be parsed by scripts.

Please provide a commandline utility that tells '0' if no updates are available, and
'1' if some updates are available.

I would not mind having the same functionality available in C, but I found no
mention of it on the https://wiki.debian.org/Apt page.

*** End of the template - remove these template lines ***


-- Package-specific info:

-- (no /etc/apt/preferences present) --


-- (no /etc/apt/preferences.d/* present) --


-- (/etc/apt/sources.list present, but not submitted) --


-- (/etc/apt/sources.list.d/elastic-6.x.list present, but not submitted) --


-- (/etc/apt/sources.list.d/elastic-6.x.list~ present, but not submitted) --


-- (/etc/apt/sources.list.d/google-chrome.list present, but not submitted) --


-- (/etc/apt/sources.list.d/jitsi-stable.list present, but not submitted) --


-- (/etc/apt/sources.list.d/matrix-org.list present, but not submitted) --


-- (/etc/apt/sources.list.d/matrix-org.list~ present, but not submitted) --


-- (/etc/apt/sources.list.d/parsoid.list present, but not submitted) --


-- (/etc/apt/sources.list.d/parsoid.list~ present, but not submitted) --


-- (/etc/apt/sources.list.d/ring-nightly-main.list present, but not submitted) --


-- (/etc/apt/sources.list.d/ring-nightly-main.list~ present, but not submitted) --


-- (/etc/apt/sources.list.d/skype-stable.list present, but not submitted) --


-- (/etc/apt/sources.list.d/webmin.list present, but not submitted) --


-- (/etc/apt/sources.list.d/x2go.list present, but not submitted) --


-- (/etc/apt/sources.list.d/yarn.list present, but not submitted) --


-- (/etc/apt/sources.list.d/yarn.list~ present, but not submitted) --


-- System Information:
Debian Release: 10.0
  APT prefers testing
  APT policy: (500, 'testing'), (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.19.0-1-amd64 (SMP w/2 CPU cores)
Kernel taint flags: TAINT_WARN
Locale: LANG=ru_RU.UTF-8, LC_CTYPE=ru_RU.UTF-8 (charmap=UTF-8), LANGUAGE=ru_RU:ru (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages apt depends on:
ii  adduser                 3.118
ii  debian-archive-keyring  2019.1
ii  gpgv                    2.2.12-1
ii  libapt-pkg5.0           1.8.2
ii  libc6                   2.28-10
ii  libgcc1                 1:8.3.0-6
ii  libgnutls30             3.6.7-4
ii  libseccomp2             2.3.3-4
ii  libstdc++6              8.3.0-6

Versions of packages apt recommends:
ii  ca-certificates  20190110

Versions of packages apt suggests:
pn  apt-doc         <none>
ii  aptitude        0.8.11-7
ii  dpkg-dev        1.19.7
ii  gnupg           2.2.12-1
ii  gnupg2          2.2.12-1
ii  powermgmt-base  1.34
ii  synaptic        0.84.6

-- no debconf information