Gestion liens symboliques vers les programmes par défaut.
https://www.redhat.com/sysadmin/alternatives-command
https://unix.stackexchange.com/questions/334707/what-is-the-meaning-of-update-alternatives-config-java-command
Dossier des noms génériques : /etc/alternatives
Dossier d'administration : /var/lib/alternatives
update-alternativesest un alias vers alternatives
$ ls -l /usr/sbin/alternatives
-rwxr-xr-x. 1 root root 28K Apr 6 2020 /usr/sbin/alternatives
$ ls -l /usr/sbin/update-alternatives
lrwxrwxrwx. 1 root root 12 Jan 23 2021 /usr/sbin/update-alternatives -> alternativesLister tous les noms génériques.
$ sudo alternatives --list
libnssckbi.so.x86_64 auto /usr/lib64/pkcs11/p11-kit-trust.so
pax auto /usr/bin/spax
ld auto /usr/bin/ld.bfd
print auto /usr/bin/lpr.cups
cifs-idmap-plugin auto /usr/lib64/cifs-utils/cifs_idmap_sss.so
mta auto /usr/sbin/sendmail.postfix
ksh auto /bin/ksh93
cups_backend_smb auto /usr/bin/smbspool
java manual /usr/lib/jvm/java-11-openjdk-11.0.22.0.7-1.el7_9.x86_64/bin/java
jre_openjdk auto /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.402.b06-1.el7_9.x86_64/jre
jre_1.6.0 auto /usr/lib/jvm/jre-1.6.0-openjdk.x86_64
javac auto /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.402.b06-1.el7_9.x86_64/bin/javac
java_sdk_openjdk auto /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.402.b06-1.el7_9.x86_64
java_sdk_1.6.0 auto /usr/lib/jvm/java-1.6.0-openjdk.x86_64
jre_1.7.0 auto /usr/lib/jvm/java-1.7.0-openjdk-1.7.0.261-2.6.22.2.el7_8.x86_64/jre
jre_1.7.0_openjdk auto /usr/lib/jvm/jre-1.7.0-openjdk-1.7.0.261-2.6.22.2.el7_8.x86_64
java_sdk_1.7.0 auto /usr/lib/jvm/java-1.7.0-openjdk-1.7.0.261-2.6.22.2.el7_8.x86_64
java_sdk_1.7.0_openjdk auto /usr/lib/jvm/java-1.7.0-openjdk-1.7.0.261-2.6.22.2.el7_8.x86_64
jre_1.8.0 auto /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.402.b06-1.el7_9.x86_64/jre
jre_1.8.0_openjdk auto /usr/lib/jvm/jre-1.8.0-openjdk-1.8.0.402.b06-1.el7_9.x86_64
java_sdk_1.8.0 auto /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.402.b06-1.el7_9.x86_64
java_sdk_1.8.0_openjdk auto /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.402.b06-1.el7_9.x86_64
jre_11 auto /usr/lib/jvm/java-11-openjdk-11.0.22.0.7-1.el7_9.x86_64
jre_11_openjdk auto /usr/lib/jvm/jre-11-openjdk-11.0.22.0.7-1.el7_9.x86_64
nmap auto /usr/bin/ncat
libwbclient.so.0.15-64 auto /usr/lib64/samba/wbclient/libwbclient.so.0.15
java_sdk_11 auto /usr/lib/jvm/java-11-openjdk-11.0.22.0.7-1.el7_9.x86_64
java_sdk_11_openjdk auto /usr/lib/jvm/java-11-openjdk-11.0.22.0.7-1.el7_9.x86_64
emacs.etags auto /usr/bin/etags.emacs
emacs auto /usr/bin/emacs-24.3Ajouter un nom générique.
# LOCATION-OF-GENERIC-SYMLINK GENERIC-ALTERNATIVE-NAME CALLED-BINARY PRIORITY (plus le nombre est élevé, plus grande est la priorité)
# ce qui donne la chaine de liens symboliques suivante : /usr/bin/em ---> /etc/alternatives/em ---> /opt/em-legacy/em2
$ sudo alternatives --install /usr/bin/em uemacs /opt/em-legacy/em2 1
$ sudo alternatives --install /usr/bin/em uemacs /usr/local/bin/nem 99Configurer un lien symbolique alternatif.
$ sudo alternatives --config uemacs
There are 2 programs which provide 'uemacs'.
Selection Command
-----------------------------------------------
*+ 1 /usr/local/bin/nem
2 /opt/em-legacy/em2* = choix par défaut en mode auto (aka. plus grande priorité)
+ = choix actuel
Supprimer un nom générique et tous ses liens potentiels : sudo alternatives --remove-all uemacs
Supprimer un choix possible d'un nom générique : sudo alternatives --remove uemacs /opt/em-legacy/em2
OS name
$ hostnamectl
Static hostname: xxx.domain
Icon name: computer-vm
Chassis: vm
Machine ID: 1432cbf7b9314ef5ac2ae3e15bf56e5e
Boot ID: 274e1417a42c4b01a46952f9e55067ae
Virtualization: vmware
Operating System: CentOS Linux 7 (Core)
CPE OS Name: cpe:/o:centos:centos:7
Kernel: Linux 3.10.0-327.el7.x86_64
Architecture: x86-64
$ cat /etc/redhat-release (centos output)
CentOS Linux release 7.2.1511 (Core)
$ cat /etc/redhat-release (rhel output)
Red Hat Enterprise Linux Server release 7.9 (Maipo)
RHEL 8
$ sudo yum repolist
Updating Subscription Management repositories.
repo id repo name
docker-ce-stable Docker CE Stable - x86_64
rhel-8-for-x86_64-appstream-rpms Red Hat Enterprise Linux 8 for x86_64 - AppStream (RPMs)
rhel-8-for-x86_64-baseos-rpms Red Hat Enterprise Linux 8 for x86_64 - BaseOS (RPMs)
$ sudo yum -y install https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm
Updating Subscription Management repositories.
Last metadata expiration check: 2:36:11 ago on Wed 17 Apr 2024 02:21:46 PM CEST.
epel-release-latest-8.noarch.rpm 6.1 kB/s | 25 kB 00:04
Dependencies resolved.
========================================================================================================================================================================================
Package Architecture Version Repository Size
========================================================================================================================================================================================
Installing:
epel-release noarch 8-19.el8 @commandline 25 k
Transaction Summary
========================================================================================================================================================================================
Install 1 Package
Total size: 25 k
Installed size: 35 k
Downloading Packages:
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
Preparing : 1/1
Installing : epel-release-8-19.el8.noarch 1/1
Running scriptlet: epel-release-8-19.el8.noarch 1/1
Many EPEL packages require the CodeReady Builder (CRB) repository.
It is recommended that you run /usr/bin/crb enable to enable the CRB repository.
Verifying : epel-release-8-19.el8.noarch 1/1
Installed products updated.
Installed:
epel-release-8-19.el8.noarch
Complete!
$ sudo yum repolist
Updating Subscription Management repositories.
repo id repo name
docker-ce-stable Docker CE Stable - x86_64
epel Extra Packages for Enterprise Linux 8 - x86_64
rhel-8-for-x86_64-appstream-rpms Red Hat Enterprise Linux 8 for x86_64 - AppStream (RPMs)
rhel-8-for-x86_64-baseos-rpms Red Hat Enterprise Linux 8 for x86_64 - BaseOS (RPMs)Making CA certificates available to Linux command-line tools
How to configure your CA trust list in Linux
OpenJDK cacerts file is being overwritten
update-ca-trust man
Endpointdev : versions récentes des programmes
EPEL : Extra Packages for Enterprise Linux
Remi repo : repo proposants des versions récentes de PHP
Software collections (SCL) : versions récentes et alternatives des programmes dans un file system séparé
(déprécié à partir de RHEL 8, remplacé par les appstreams cf. blog post)
https://www.softwarecollections.org/en/
Activer repo : sudo yum-config-manager --enable rhel-server-rhscl-7-rpms
(activé dans /etc/yum.repos.d/redhat.repo)
Exécuter une commande avec un (ou plusieurs) SCL activé(s) : scl enable software_collection... 'command...'
Nouvelle session avec un (ou plusieurs) SCL activé(s) : scl enable software_collection... bash
ntsysv, chkconfig and service commands for RHEL 6 and before.
systemd commands for RHEL 7 and after.
/etc/rc.d/init.d
Beaucoup de liens symboliques comme /etc/rcX.d, /etc/init.d vers leurs équivalents dans /etc/rc.d/init.d.
sudo ntsysv # configure for current level only
sudo ntsysv --level 35 # configure for selected levels
Example of chkconfig headers :
# chkconfig: 345 90 10
# description: My service description
chkconfig # same as --list
chkconfig --list # list all services
chkconfig --list service_name # list selected service
chkconfig service_name on # enable service in runlevels 2, 3, 4, and 5
chkconfig service_name on --level 35 # enable service in eg. selected runlevels 3 and 5 (not supported for xinetd services, just use first form)
chkconfig service_name off # disable service in runlevels 2, 3, 4, and 5
chkconfig service_name off --level 24 # disable service in eg. selected runlevels 2 and 4 (not supported for xinetd services, just use first form)
sudo chkconfig --add service_name # add service in /etc/rc.d/rcX.d according to chkconfig headers in init script
sudo chkconfig --del service_name # delete service in /etc/rc.d/rcX.d according to chkconfig headers in init scriptservice service_name status # check a service status
service --status-all # check all services status
service service_name start # start a service
service service_name stop # stop a service
service service_name restart # restart a service