Informatique

CURL

Set up Host header

1
curl -H 'Host: example.com' http://203.0.113.10/path
curl --resolve example.com:443:203.0.113.10 https://example.com/path

As telnet

1
curl -v telnet://10.26.4.124:30984

LVM

scan des lvm

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# lvscan 
  inactive          '/dev/lvm2/root' [3.47 GiB] inherit
  ACTIVE            '/dev/lvm/data' [1.80 TiB] inherit

activer un volume inactif

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# lvchange -y /dev/lvm2/root

activer tous les volumes inactifs

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# lvchange -ya

use 100%

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# lvextend -l 100%FREE /dev/VolGroup00/lv_root

NFS

Troubleshooting

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Feb 21 10:23:47 nfs-01 systemd[1]: Starting NFS server and services...
Feb 21 10:23:48 nfs-01 rpc.nfsd[15655]: error starting threads: errno 12 (Cannot allocate memory)


sync && echo 3 > /proc/sys/vm/drop_caches

date

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date  --date="STRING"
date  --date="next Friday"
date  -d "2 days ago"
date  --date="yesterday"
date  --date="yesterday" +"%format"
# Get yesterday's date in dd-mm-yy format
date  --date="yesterday" +"%d-%m-%y"
date  -d "yesterday" +"%m-%d-%y" # US date format
date  --date="yesterday" +"%Y-%m-%d" # YYYY-mm-dd format
## store y'day date in a shell variable called yday and display it ##
yday=$(date  --date="yesterday" +"%Y-%m-%d")
echo "$yday"


date -d 'now -20 hours'

read timestamp

1
date -d @1674634504
mercredi 25 janvier 2023, 09:15:04 (UTC+0100)

Keystore

Java Keytool Commands for Creating and Importing
These commands allow you to generate a new Java Keytool keystore file, create a CSR, and import certificates. Any root or intermediate certificates will need to be imported before importing the primary certificate for your domain.

Generate a Java keystore and key pair

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keytool -genkey -alias mydomain -keyalg RSA -keystore keystore.jks  -keysize 2048

Generate a certificate signing request (CSR) for an existing Java keystore

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keytool -certreq -alias mydomain -keystore keystore.jks -file mydomain.csr

Import a root or intermediate CA certificate to an existing Java keystore

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keytool -import -trustcacerts -alias root -file Thawte.crt -keystore keystore.jks

Import a signed primary certificate to an existing Java keystore

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keytool -import -trustcacerts -alias mydomain -file mydomain.crt -keystore keystore.jks

Generate a keystore and self-signed certificate (see How to Create a Self Signed Certificate using Java Keytoolfor more info)

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keytool -genkey -keyalg RSA -alias selfsigned -keystore keystore.jks -storepass password -validity 360 -keysize 2048

Java Keytool Commands for Checking
If you need to check the information within a certificate, or Java keystore, use these commands.

Check a stand-alone certificate

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keytool -printcert -v -file mydomain.crt

Check which certificates are in a Java keystore

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keytool -list -v -keystore keystore.jks

Check a particular keystore entry using an alias

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keytool -list -v -keystore keystore.jks -alias mydomain

Other Java Keytool Commands
Delete a certificate from a Java Keytool keystore

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keytool -delete -alias mydomain -keystore keystore.jks

Change a Java keystore password

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keytool -storepasswd -new new_storepass -keystore keystore.jks

Export a certificate from a keystore

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keytool -export -alias mydomain -file mydomain.crt -keystore keystore.jks

List Trusted CA Certs

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keytool -list -v -keystore $JAVA_HOME/jre/lib/security/cacerts

Import New CA into Trusted Certs

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keytool -import -trustcacerts -file /path/to/ca/ca.pem -alias CA_ALIAS -keystore $JAVA_HOME/jre/lib/security/cacerts

COUCHDB

Healthcheck

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# curl -s http://$COUCHDB_USER:$COUCHDB_PASSWORD@localhost:5984/_up  | jq

List all databases

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# curl -s http://$COUCHDB_USER:$COUCHDB_PASSWORD@localhost:5984/_all_dbs  | jq

Database info

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# curl -s http://$COUCHDB_USER:$COUCHDB_PASSWORD@localhost:5984/<db>  | jq

List all docs from a database

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# curl -s http://$COUCHDB_USER:$COUCHDB_PASSWORD@localhost:5984/<db>/_all_docs  | jq

Info from a doc

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# curl -s http://$COUCHDB_USER:$COUCHDB_PASSWORD@localhost:5984/<db>/<id_doc>  | jq

Restart

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# curl -s -X POST -H"Content-Type: application/json" -u $COUCHDB_USER:$COUCHDB_PASSWORD localhost:5984/_node/couchdb@<node_name>/_restart

List member of a cluster

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# curl -s http://$COUCHDB_USER:$COUCHDB_PASSWORD@localhost:5984/_membership  | jq

add member

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# curl -s -u $COUCHDB_USER:$COUCHDB_PASSWORD -X PUT "http://localhost:5986/_nodes/couchdb@<node_name>" -d {}

get rev

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# curl -s -u $COUCHDB_USER:$COUCHDB_PASSWORD  "http://localhost:5986/_nodes/couchdb@<node_name>"

del member

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# curl -s -u $COUCHDB_USER:$COUCHDB_PASSWORD -X DELETE "http://localhost:5986/_nodes/couchdb@<node_name>?rev=1-967a00dff5e02add41820138abb3284d"

set/unset maintenance mode

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# curl -s -u $COUCHDB_USER:$COUCHDB_PASSWORD -X PUT -H "Content-type: application/json" localhost:5984/_node/couchdb@<node_name>/_config/couchdb/maintenance_mode -d "\"false\""

Show config

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# curl -s -u $COUCHDB_USER:$COUCHDB_PASSWORD -X GET -H "Content-type: application/json" localhost:5984/_node/couchdb@<node_name>/_config/couchdb
# curl -s -u $COUCHDB_USER:$COUCHDB_PASSWORD -X GET -H "Content-type: application/json" localhost:5984/_node/couchdb@<node_name>/_config

Force db syn

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# curl -s -X POST -H"Content-Type: application/json" -u $COUCHDB_USER:$COUCHDB_PASSWORD localhost:5984/<db>/_sync_shards

ip

  • show ip

    1
    ip -4 addr show
ip -4 -o addr show

  • set up ip 

    1
    ip addr add 192.168.50.2/24 dev ens160

  • unset ip

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    ip addr del 192.168.1.5/24 dev eth0

  • link up 

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    ip link set eth0 up

  • link down

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    ip link set eth0 down

  • add default gw

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    ip route add default via 192.168.1.1

  • add gw

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    ip route add 10.0.0.0/8 dev eth0

XFS

get info

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~# xfs_info /mnt/plop

check fragmentation

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~# xfs_db -r -c 'frag' /dev/plop

defrag

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~# xfs_fsr

repair

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~# xfs_repair (-L) -m 20480 /dev/plop

( flush cache)

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~# echo 1 > /proc/sys/vm/drop_caches
~# echo 2 > /proc/sys/vm/drop_caches