diff --git a/tldr/ffmpeg b/tldr/ffmpeg
index c30b7ba2..388fcce5 100644
--- a/tldr/ffmpeg
+++ b/tldr/ffmpeg
@@ -19,7 +19,7 @@ source: https://github.com/tldr-pages/tldr.git
 
 - Save a video as GIF, scaling the height to 1000px and setting framerate to 15:
 
-`ffmpeg -i {{path/to/video.mp4}} {{[-vf|-filter:v]}} 'scale=-1:{{1000}}' -r {{15}} {{path/to/output.gif}}`
+`ffmpeg -i {{path/to/video.mp4}} {{[-vf|-filter:v]}} 'scale=-1:1000' -r 15 {{path/to/output.gif}}`
 
 - Combine numbered images (`frame_1.jpg`, `frame_2.jpg`, etc) into a video or GIF:
 
diff --git a/tldr/linux/apptainer b/tldr/linux/apptainer
new file mode 100644
index 00000000..a3051b05
--- /dev/null
+++ b/tldr/linux/apptainer
@@ -0,0 +1,42 @@
+---
+syntax: markdown
+tags: [tldr, linux]
+source: https://github.com/tldr-pages/tldr.git
+---
+# apptainer
+
+> Manage containers for HPC and scientific computing.
+> Some subcommands such as `build`, `pull`, and `push` have their own usage documentation.
+> More information: <https://apptainer.org/docs/user/main/cli.html>.
+
+- Download a container from Docker Hub:
+
+`apptainer pull {{path/to/image.sif}} docker://{{image}}:{{tag}}`
+
+- Download a container from the Container Library:
+
+`apptainer pull {{path/to/image.sif}} library://{{user/collection/container}}:{{tag}}`
+
+- Build a container from a definition file:
+
+`apptainer build {{path/to/image.sif}} {{path/to/definition.def}}`
+
+- Start an interactive shell inside a container:
+
+`apptainer shell {{path/to/image.sif}}`
+
+- Execute a command inside a container:
+
+`apptainer exec {{path/to/image.sif}} {{command}}`
+
+- Run the default runscript of a container:
+
+`apptainer run {{path/to/image.sif}}`
+
+- Inspect a container's metadata:
+
+`apptainer inspect {{path/to/image.sif}}`
+
+- Display help:
+
+`apptainer {{[-h|--help]}}`
diff --git a/tldr/linux/apptainer-build b/tldr/linux/apptainer-build
new file mode 100644
index 00000000..05fa59af
--- /dev/null
+++ b/tldr/linux/apptainer-build
@@ -0,0 +1,41 @@
+---
+syntax: markdown
+tags: [tldr, linux]
+source: https://github.com/tldr-pages/tldr.git
+---
+# apptainer build
+
+> Build Apptainer container images.
+> More information: <https://apptainer.org/docs/user/main/cli/apptainer_build.html>.
+
+- Build a container from a definition file:
+
+`apptainer build {{path/to/image.sif}} {{path/to/definition.def}}`
+
+- Build a container from Docker Hub:
+
+`apptainer build {{path/to/image.sif}} docker://{{image}}:{{tag}}`
+
+- Build a container from the Container Library:
+
+`apptainer build {{path/to/image.sif}} library://{{user/collection/container}}:{{tag}}`
+
+- Build a writable [s]andbox directory instead of an image file:
+
+`apptainer build {{[-s|--sandbox]}} {{path/to/directory}} docker://{{image}}:{{tag}}`
+
+- Build a container without using the cache:
+
+`apptainer build --disable-cache {{path/to/image.sif}} docker://{{image}}:{{tag}}`
+
+- [F]orce overwrite an existing image file:
+
+`apptainer build {{[-F|--force]}} {{path/to/image.sif}} {{path/to/definition.def}}`
+
+- Build using [f]akeroot for unprivileged builds:
+
+`apptainer build {{[-f|--fakeroot]}} {{path/to/image.sif}} {{path/to/definition.def}}`
+
+- Display help:
+
+`apptainer build {{[-h|--help]}}`
diff --git a/tldr/linux/apptainer-pull b/tldr/linux/apptainer-pull
new file mode 100644
index 00000000..919c2416
--- /dev/null
+++ b/tldr/linux/apptainer-pull
@@ -0,0 +1,42 @@
+---
+syntax: markdown
+tags: [tldr, linux]
+source: https://github.com/tldr-pages/tldr.git
+---
+# apptainer pull
+
+> Pull container images from remote sources.
+> See also: `apptainer-push`.
+> More information: <https://apptainer.org/docs/user/main/cli/apptainer_pull.html>.
+
+- Pull a container from Docker Hub:
+
+`apptainer pull {{path/to/image.sif}} docker://{{image}}:{{tag}}`
+
+- Pull a container from the Container Library:
+
+`apptainer pull {{path/to/image.sif}} library://{{user/collection/container}}:{{tag}}`
+
+- Pull a container from an OCI registry:
+
+`apptainer pull {{path/to/image.sif}} oras://{{registry/namespace/image}}:{{tag}}`
+
+- Pull a container for a specific architecture:
+
+`apptainer pull --arch {{amd64|arm64|ppc64le}} {{path/to/image.sif}} library://{{image}}:{{tag}}`
+
+- [F]orce overwrite an existing image file:
+
+`apptainer pull {{[-F|--force]}} {{path/to/image.sif}} docker://{{image}}:{{tag}}`
+
+- Pull a container as a writable sandbox directory:
+
+`apptainer pull --sandbox {{path/to/directory}} docker://{{image}}:{{tag}}`
+
+- Pull a container without using the cache:
+
+`apptainer pull --disable-cache {{path/to/image.sif}} docker://{{image}}:{{tag}}`
+
+- Display help:
+
+`apptainer pull {{[-h|--help]}}`
diff --git a/tldr/linux/apptainer-push b/tldr/linux/apptainer-push
new file mode 100644
index 00000000..9f5a9993
--- /dev/null
+++ b/tldr/linux/apptainer-push
@@ -0,0 +1,30 @@
+---
+syntax: markdown
+tags: [tldr, linux]
+source: https://github.com/tldr-pages/tldr.git
+---
+# apptainer push
+
+> Push container images to remote registries.
+> See also: `apptainer-pull`.
+> More information: <https://apptainer.org/docs/user/main/cli/apptainer_push.html>.
+
+- Push a container to the Container Library:
+
+`apptainer push {{path/to/image.sif}} library://{{user/collection/container}}:{{tag}}`
+
+- Push a container to an OCI registry:
+
+`apptainer push {{path/to/image.sif}} oras://{{registry/namespace/image}}:{{tag}}`
+
+- Push an [U]nsigned container (skip signature verification):
+
+`apptainer push {{[-U|--allow-unsigned]}} {{path/to/image.sif}} library://{{user/collection/container}}:{{tag}}`
+
+- Push a container with a [D]escription (library only):
+
+`apptainer push {{[-D|--description]}} "{{description}}" {{path/to/image.sif}} library://{{user/collection/container}}:{{tag}}`
+
+- Display help:
+
+`apptainer push {{[-h|--help]}}`
diff --git a/tldr/trdsql b/tldr/trdsql
index a39bc87e..9ff6d7f6 100644
--- a/tldr/trdsql
+++ b/tldr/trdsql
@@ -18,7 +18,7 @@ source: https://github.com/tldr-pages/tldr.git
 
 - Manipulate complex SQL query with data from multiple CSV files with first line is header (`-ih`):
 
-`trdsql -icsv -ih "SELECT {{column1,column2}} FROM {{path/to/file*.csv}} WHERE column2 != '' ORDER BY column1 GROUP BY column1"`
+`trdsql -icsv -ih "SELECT {{column1,column2}} FROM {{path/to/file*.csv}} WHERE column2 != '' ORDER BY {{column1}} GROUP BY {{column1}}"`
 
 - Merge content of 2 CSV files to one CSV file: