gdb, git, strace

how_to

@@ -985,20 +985,61 @@ ssh:
             ssh -R 2222:localhost:22 <user>@<server>
         from server:
             ssh -p 2222 <user>@127.0.0.1
-
-Transfer files without using ssh/scp:
-    # Credits: @Chapoline, @britaliope
-    Server-side (untars in current directory):
-        # directory
-            nc -l -p 1234 | openssl enc -aes-256-cbc -d -iter 1000 | tar -xzf -
-        # file
-            nc -l -p 1234 | openssl enc -aes-256-cbc -d -iter 1000 | gunzip - > <file>
-    Client-side:
-        # directory
-            tar -zc <dir> -c | openssl enc -aes-256-cbc -e -iter 1000 | nc <ip> 1234 -q 1
-        # file
-            gzip <file> -c | openssl enc -aes-256-cbc -e -iter 1000 | nc <ip> 1234 -q 1
-    # Both need the same passphrase in stdin
+    X11 forwarding (with wayland):
+        Remote:
+            sudo pacman -S xorg-xauth
+            /etc/ssh/sshd_config
+                X11Forwarding yes
+                # (default values)
+                AllowTcpForwarding yes
+                X11UseLocalhost yes
+                X11DisplayOffset 10
+            sudo sv restart sshd
+        Client:
+            sudo pacman -S xorg-xauth xorg-xwayland
+            # Restart sway
+            ssh -X <user>@<remote>
+
+openssl:
+    Transfer files without using ssh/scp:
+        # Credits: @Chapoline, @britaliope
+        Server-side (untars in current directory):
+            # directory
+                nc -l -p 1234 | openssl enc -aes-256-cbc -d -iter 1000 | tar -xzf -
+            # file
+                nc -l -p 1234 | openssl enc -aes-256-cbc -d -iter 1000 | gunzip - > <file>
+        Client-side:
+            # directory
+                tar -zc <dir> -c | openssl enc -aes-256-cbc -e -iter 1000 | nc <ip> 1234 -q 1
+            # file
+                gzip <file> -c | openssl enc -aes-256-cbc -e -iter 1000 | nc <ip> 1234 -q 1
+        # Both need the same passphrase in stdin
+
+    Manual IMAP connection:
+        # https://www.atmail.com/blog/imap-101-manual-imap-sessions/
+        # https://stackoverflow.com/questions/14959461/how-to-talk-to-imap-server-in-shell-via-openssl
+        # https://gist.github.com/fedir/1d8f8fb8a5f80090705ef7793936216a²
+
+        $ openssl s_client -connect <imap server>:993 -crlf [-quiet]
+        $ openssl s_client -connect <imap server>:143 -crlf -starttls imap [-quiet]
+        # IMAP needs an incrementing prefix before each command
+        A1 login <login> "<password>"
+        # list everything
+        A2 list "" "*"
+        # list everything under a particular prefix
+        A3 list "INBOX" "*"
+        # Or:
+        # (will print current UIDVALIDITY (useful for fixing mbsync))
+        A4 select inbox
+        A99 logout
+
+    Check SSL/TLS certificate expiration date:
+        echo | openssl s_client -servername <name.example.tld> -connect <example.tld>:443 2>/dev/null | openssl x509 -noout -dates
+
+    Add a CA to the system trust store (archlinux):
+        # https://wiki.archlinux.org/title/Transport_Layer_Security#Trust_management
+        sudo cp cacert.crt /etc/ca-certificates/trust-source/anchors/cacert.crt
+        sudo update-ca-trust extract
 
 
 Run MSVC on linux with Wine:
@@ -1028,9 +1069,45 @@ Run studiotax on wine:
     wine ./StudioTax2017Install.exe /extract
     msiexec /i StudioTax.msi
 
-Easily switch to russian phonetic keyboard:
-    setxkbmap fr,ru -variant ,phonetic -option grp:shift_caps_toggle
-    man xkeyboard-config  # get list of possible toggles
+Xkb:
+    Easily switch to russian phonetic keyboard:
+        setxkbmap fr,ru -variant ,phonetic -option grp:shift_caps_toggle
+        man xkeyboard-config  # get list of possible toggles
+
+    Customisation notes:
+        - https://web.archive.org/web/20190724015820/http://pascal.tsu.ru/en/xkb
+        - https://gitlab.freedesktop.org/xkeyboard-config/xkeyboard-config/-/blob/master/docs/README.enhancing?ref_type=heads
+        - https://xkbcommon.org/doc/current/group__state.html#consumed-modifiers
+        - https://xkbcommon.org/doc/current/user-configuration.html
+        - https://xkbcommon.org/doc/current/user-configuration.html#autotoc_md16
+        - https://xkbcommon.org/doc/current/rule-file-format.html
+        - https://www.charvolant.org/doug/xkb/html/xkb.html
+        - https://medium.com/@damko/a-simple-humble-but-comprehensive-guide-to-xkb-for-linux-6f1ad5e13450
+        - https://github.com/isti115/dotfiles/blob/master/.config/xkb/symbols/Lenovo-Y50
+        - https://unix.stackexchange.com/a/101417
+        - https://delapouite.com/ramblings/xkb-walkthrough/
+        - https://github.com/xkbcommon/libxkbcommon/issues/17
+        - https://stackoverflow.com/a/45042841
+
+        Libxkbcommon is more flexible and modern in term of looking to ~/.xkb
+        and ~/.config/xkb as well as /usr/share/X11/xkb for config, but
+        unfortunately X11(?) isn't, and will only look into the system path.
+
+        Except for a single `custom` layout left free:
+            - https://blog.nemirwen.me/posts/fr-oss-ansi-xkb-layout
+            - https://gitlab.freedesktop.org/xkeyboard-config/xkeyboard-config/-/merge_requests/189/diffs
+
+        Also while libxkbcommon seems to rely more on rules files, X11 and so
+        setxkbmap seems to rely more on the xml descriptors. (supposition)
+        Also xorg's XKB rules syntax doesn't have %S or %H for recursive includes
+        `strace` is a very good tool to debug this mess.
+
+        Most people on the internet seem to rely on editing existing layout,
+        which feels icky to me.
+
+    Custom key type for Ctrl+Alt as AltGr:
+        - https://unix.stackexchange.com/a/187495
+
 
 Image/photo sorting with feh:
     feh --action1 'mv -v %F "/path/to/target/"%N' \
@@ -1140,24 +1217,6 @@ Mounting .bin/.cue image files:
     $ bchunk file.bin file.cue output
     $ sudo mount output01.iso /mnt -o loop,ro
 
-Manual IMAP connection:
-    # https://www.atmail.com/blog/imap-101-manual-imap-sessions/
-    # https://stackoverflow.com/questions/14959461/how-to-talk-to-imap-server-in-shell-via-openssl
-    # https://gist.github.com/fedir/1d8f8fb8a5f80090705ef7793936216a²
-
-    $ openssl s_client -connect <imap server>:993 -crlf [-quiet]
-    $ openssl s_client -connect <imap server>:143 -crlf -starttls imap [-quiet]
-    # IMAP needs an incrementing prefix before each command
-    A1 login <login> "<password>"
-    # list everything
-    A2 list "" "*"
-    # list everything under a particular prefix
-    A3 list "INBOX" "*"
-    # Or:
-    # (will print current UIDVALIDITY (useful for fixing mbsync))
-    A4 select inbox
-    A99 logout
-
 gdb tricks:
     Easily print attributes of array elements:
         # https://agateau.com/2008/gdb-trick-the-poor-man-loop
@@ -1171,6 +1230,11 @@ gdb tricks:
         (gdb) while ($i < <length>)
         > print foo[$i++].attribute
         > end
+    Dynamic printf:
+        # Breakpoint that prints instead of stopping
+        # https://sourceware.org/gdb/current/onlinedocs/gdb.html/Dynamic-Printf.html
+        # https://developers.redhat.com/articles/2021/10/13/printf-style-debugging-using-gdb-part-2
+        (gdb) dprintf meow.c:42,"foo:%d bar:%s\n", number, string
 
 Non-standard zsh cd trick:
     # https://dataswamp.org/~solene/2020-09-04-cd-command.html
@@ -1189,6 +1253,12 @@ Git:
         git config url."git@example.org:user/".pushInsteadOf "https://example.org/user/"
     Prevent git from trying to auto-detect user name and email:
         user.useConfigOnly = true
+    Revert a rebase after continue/commit:
+        # https://stackoverflow.com/a/135614
+        # Find last sane state (prefixed with "commit:" instead of "rebase:"
+        git reflog
+        # /!\ Be careful to either your modifications or remember what you did
+        git reset --hard 'HEAD@{<n>}'
 
 Setup a midi synth:
     # http://www.tedfelix.com/linux/linux-midi.html
@@ -1351,9 +1421,6 @@ Jupyter:
         jupyter nbconvert --clear-output \
             --to notebook --output=my_notebook_no_out my_notebook.ipynb
 
-Check SSL/TLS certificate expiration date:
-    echo | openssl s_client -servername <name.example.tld> -connect <example.tld>:443 2>/dev/null | openssl x509 -noout -dates
-
 List files in chronological order with ls:
     # https://shkspr.mobi/blog/2020/12/anatomy-of-an-ls-command/
     ls -trhgGN --color=always | cut -d" " -f3-
@@ -1363,3 +1430,7 @@ Change default java environment (archlinux):
     archlinux-java status
     # Example
     archlinux set java-18-openjdk
+
+strace:
+    print all file access:
+        strace -yy -f -e trace=file -- <bin>