diff --git a/docs/software/cheatsheet/exiftool.md b/docs/software/cheatsheet/exiftool.md
new file mode 100644
index 0000000..877f7bf
--- /dev/null
+++ b/docs/software/cheatsheet/exiftool.md
@@ -0,0 +1,17 @@
+Rename all files so their filename is the creation date timestamp:
+
+```shell
+exiftool -d '%Y-%m-%d_%H%M%S.%%e' '-filename<CreateDate' .
+```
+
+Set the metadata timestamp to match the filename:
+```shell
+exiftool "-datetimeoriginal<filename" -overwrite_original ./
+# or
+exiftool "-alldates<filename" -overwrite_original ./
+```
+
+Clear all exif data:
+```shell
+exiftool -all= −overwrite_original ./
+```
diff --git a/docs/software/cheatsheet/remote-host.md b/docs/software/cheatsheet/remote-host.md
index f0e0f94..106b8ea 100644
--- a/docs/software/cheatsheet/remote-host.md
+++ b/docs/software/cheatsheet/remote-host.md
@@ -14,6 +14,25 @@ systemctl list-timers
 
 ```
 
+## journalctl
+```shell
+journalctl --since 08:55:00 --no-pager | less
+```
+
+## sysstat
+Install sysstat
+```shell
+sudo apt install sysstat
+sed -i 's/ENABLED="false"/ENABLED="true"/' /etc/default/sysstat
+systemctl restart sysstat sysstat-collect.timer sysstat-summary.timer
+```
+
+Then inspect:
+
+```shell
+sar -r -q -f /var/log/sysstat/{sa_for_that_day} -s 17:50:01 -e 18:01:01
+```
+
 ## Unexpected pod restarts
 Get restart count per pod:
 ```bash
diff --git a/docs/software/cheatsheet/ssh.md b/docs/software/cheatsheet/ssh.md
index af9479d..8862c72 100644
--- a/docs/software/cheatsheet/ssh.md
+++ b/docs/software/cheatsheet/ssh.md
@@ -59,3 +59,20 @@ ssh -i ~/secrets/tailscale-ssh \
   -o "StrictHostKeyChecking no" \
   user@remote
 ```
+
+## Generate SSH key for GitHub
+```shell
+ssh-keygen -t ed25519 -C "82407168+sed-i@users.noreply.github.com" -N "" -f github_ssh
+```
+
+Refs:
+[1](https://docs.github.com/en/authentication/connecting-to-github-with-ssh/generating-a-new-ssh-key-and-adding-it-to-the-ssh-agent),
+[2](https://github.com/settings/keys)
+[3](https://docs.github.com/en/authentication/managing-commit-signature-verification/telling-git-about-your-signing-key)
+
+Then,
+```shell
+git config --global gpg.format ssh
+git config --global user.signingkey /PATH/TO/github_ssh.pub
+git config --global commit.gpgsign true  # sign all commit by default (optional)
+```
diff --git a/mkdocs.yml b/mkdocs.yml
index b145d70..6fd647c 100644
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -21,6 +21,7 @@ nav:
       - 'Remote host': 'software/cheatsheet/remote-host.md'
       - 'SSH': 'software/cheatsheet/ssh.md'
       - 'Privacy online': 'software/cheatsheet/privacy-online.md'
+      - 'Exif tool': 'software/cheatsheet/exiftool.md'
     - Reference:
       - 'Get up to speed': 'software/reference/get-up-to-speed.md'
       - Culture: 'software/reference/culture.md'