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--- code:linux [2017/03/27 17:25]
hansek
+++ code:linux [2023/11/11 00:39] (current)
hansek [jq]
@@ Line 145: / Line 145: @@
 Pro více typů zopakovat celou konstrukci **! -name '*.html'**
+Na ČH, kde je pouze `find`:
+<code bash>
+# on remote server
+find . -type f -printf "%-.22T+ %M %n %-8u %-8g %8s %Tx %.8TX %p\n" > last_changes.txt
+# on localhost
+scp remote:last_changes.txt .
+cat last_changes.txt  | sort -r | cut -f 2- -d ' ' | head -20
+# or with striping some lines
+sed '/webcam/d' last_changed.txt | sort -r | cut -f 2- -d ' ' | head -20
+</code>
 ===== Výpis 20 největších souborů na FS v rámci adresáře =====
 Vynechání některých souborů viz předchozí.
@@ Line 189: / Line 204: @@
-==== Grep DataDog logs from syslog ====
+===== Grep DataDog logs from syslog =====
 <code bash>
 tailf /var/log/syslog | grep -v "dd."
+</code>
+===== Clean up old kernels  =====
+Source: https://askubuntu.com/a/473639
+Check current version and **DO NOT REMOVE THIS KERNEL!**
+<code bash>
+uname -r
+</code>
+List all kernels
+<code bash>
+dpkg --list | grep linux-image
+</code>
+Delete/purge all kernels except current one:
+<code bash>
+sudo apt-get purge linux-image-x.x.x.x-generic
+</code>
+  * rc = Remove - only Configs
+  * ii = Install - Installed
+[[https://askubuntu.com/a/18807|Vysvětlivky falgů na začátku výpisu dpkg --list]]
+===== Disable / enable services from autostart =====
+Source: https://askubuntu.com/a/27137
+<code bash>
+sudo update-rc.d mongodb disable
+</code>
+===== Postgres restore =====
+  * -F = ''--format=c|d|t''
+  * -c = ''--clean''
+  * -O = ''--no-owner''
+  * -x = ''--no-privileges''
+  * -j5 = use 5 parallel jobs
+  * -d = database name
+<code bash>
+pg_restore -Fc -Oxv -j5 -d <database-name> <dump-file>
+</code>
+===== Journal logy =====
+Pročištění logů, odmaže starší záznamy.
+<code bash>
+sudo journalctl --vacuum-size=500M
+</code>
+Nastavení limitu pro journal v ''sudo vim /etc/systemd/journald.conf'':
+<code bash>
+SystemMaxUse=500M
+</code>
+===== Jaký proces využívá port =====
+<code bash>
+lsof -i :80
+</code>
+===== Certbot / Certifikáty =====
+List of existing certificates on host
+<code bash>
+certbot certificates
+</code>
+Certificate detailed info
+<code bash>
+openssl x509 -text -noout -in <cert-path>
+</code>
+nebo online
+<code bash>
+nmap -p 443 --script ssl-cert coex.cz
+</code>
+===== CPU iowait debug =====
+Source: https://haydenjames.io/what-is-iowait-and-linux-performance/
+<code bash>
+atop  # run it with -d option or press d to toggle the disk stats view.
+iostat -xm 2  # try it with the -xm 2 options for extended statistics, in megabytes and in two-second intervals.
+iotop -oPa  # – top-like I/O monitor. Try it with the -oPa options to show the accumulated I/O of active processes only.
+ps auxf  # – use auxf, then under the “STAT” column “D” usually indicates disk iowait.
+strace  # – view the actual operations issued by a process. Read the strace man page.
+lsof  # – after you’ve identified the process responsible, use -p [PID] to find the specific files.
+</code>
+===== jq =====
+**Inplace transform Unix timestamp to Datetime inside json log**
+<code bash>
+docker events | TZ=Europe/Prague jq '.time |= (strflocaltime("%Y-%m-%d %H:%M:%s %Z"))' -C | less
+</code>
+**Inplace decode all k8s secrets values**
+<code bash>
+kubectl get secrets postgres-secrets -o json | jq '.data | map_values(@base64d)'
 </code>

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