Various updates to .bash_profile, see full log.

Add a #! line, even though it's not required.
Use $HOME instead of ~.
Quote LESS prompt.
Rework GPG agent handling code to be more generic.
Use printf rather than echo.
A couple of code cleanups.
Make things shellcheck safe and passed.

.bash_profile

@@ -1,12 +1,14 @@
+#!/bin/bash - not strictly necessary, but helps nano with syntax highlighting.
+
 # Source bash specific set up,
-[[ -f ~/.bashrc ]] && . ~/.bashrc
+[[ -f "$HOME/.bashrc" ]] && . "$HOME/.bashrc"
 
 # Environment.
 export EDITOR="nano"
 export LANG="en_GB.UTF-8"
 export LC_COLLATE="POSIX"	# 'C' causes issues with some applications
 # export LC_CTYPE="POSIX"	# Not sure why I set this in the first place...
-export LESS="-RM -j.5 -i -PM?f%F:stdin.    --    Page %dt of %D    --    %lt/%L (%Pt\%)$"
+export LESS="-RM -j.5 -i -PM'?f%F:stdin.    --    Page %dt of %D    --    %lt/%L (%Pt\%)$'"
 export PAGER="less"
 export PATH="/opt/sbin:/usr/local/sbin:/usr/sbin:/sbin:$PATH"
 export VISUAL="$EDITOR"
@@ -15,23 +17,29 @@ hash lesspipe >/dev/null 2>&1 && eval "$(SHELL=/bin/sh lesspipe)"
 # Platform specific set up.
 PLATFORM="$(uname -s)"
 if [[ "$PLATFORM" = "Linux" ]]; then
-  # This is a hack to work around a problem with elogind/pam not creating
+  # shellcheck disable=SC2155
-  # a gnupg directory under /run/user/0 for the gpg-agent socket.
+  export GPG_TTY="$(tty)"
-  (( $(id -u) == 0 )) && [[ -e "$HOME/.gnupg/S.gpg-agent" ]] && mkdir -m 700 -p /run/user/0/gnupg && ln -sf "$HOME/.gnupg/S.gpg-agent" /run/user/0/gnupg
-  export GPG_TTY="$(tty)" && gpg-connect-agent updatestartuptty /bye >/dev/null 2>&1
   export I_WANT_A_BROKEN_PS=1
   export LYNX_CFG="$HOME/.lynx.cfg"
   export LYNX_LSS="$HOME/.lynx.lss"
   export MANPAGER="less"
   export MANPATH="$HOME/.local/share/man:$MANPATH"
-  hash dircolors >/dev/null 2>&1 && eval "$(dircolors -b ~/.dir_colors)"
+  hash dircolors >/dev/null 2>&1 && eval "$(dircolors -b "$HOME/.dir_colors")"
+  hash gpgconf >/dev/null 2>&1 && {
+    GPG_SOCK_DIR="$(gpgconf --list-dirs | awk -F : '/socketdir:/ { print $2 }')"
+    # shellcheck disable=SC2174
+    [[ ! -e "$GPG_SOCK_DIR" ]] && mkdir -m 700 -p "$GPG_SOCK_DIR"
+    [[ ! -e "$GPG_SOCK_DIR/S.gpg-agent" ]] && [[ -e "$HOME/.gnupg/S.gpg-agent" ]] && ln -sf "$HOME/.gnupg/S.gpg-agent" "$GPG_SOCK_DIR"/
+    unset GPG_SOCK_DIR
+  }
+  hash gpg-connect-agent >/dev/null 2>&1 && gpg-connect-agent updatestartuptty /bye >/dev/null 2>&1
 elif [[ "$PLATFORM" = "Darwin" ]]; then
   export LSCOLORS="ExGxdxdxCxDxDxbcacbeae"
   export MANPAGER="less -Mis -PM'Page %dt$'"
   export MANPATH="/opt/local/share/man:$MANPATH"
   export PATH="/opt/local/sbin:/opt/local/bin:$PATH"
 else
-  echo "${BASH_SOURCE##*/}: unsupported platform: $PLATFORM" >&2
+  printf "%s: %s\\n" "${BASH_SOURCE##*/}" "unsupported platform: $PLATFORM" >&2
 fi
 unset PLATFORM
 
@@ -46,46 +54,44 @@ hash screen >/dev/null 2>&1 && {
   export SCREENDIR="$HOME/.screen-${HOSTNAME%%.*}"
   if [[ -n "$SSH_TTY" ]]; then
     if [[ -n "$STY" ]]; then
-      echo "Screen $STY, window $WINDOW."
+      # shellcheck disable=SC2154
-      echo
+      printf "%s\\n\\n" "Screen $STY, window $WINDOW."
     else
       SCREENS="$(screen -ls | grep '[[:alpha:]]' | grep -E -v '^([[:digit:]]+|No) Socket(s)?')"
       if [[ -n "$SCREENS" ]]; then
-        echo "$SCREENS"
+        printf "%s\\n\\n" "$SCREENS"
-        echo
       else
-        echo "No screens."
+        printf "%s\\n\\n" "No screens."
-        echo
       fi
       unset SCREENS
     fi
   elif [[ -n "$STY" ]]; then
-    echo "Screen $STY, window $WINDOW."
+    # shellcheck disable=SC2154
-    echo
+    printf "%s\\n\\n" "Screen $STY, window $WINDOW."
   else
     TTY="$(tty | cut -d/ -f3-)"
-    SCREENS="$(screen -list | grep -F "${HOSTNAME%%.*}" | grep -F "${TTY//\//-}")"
+    SCREENS="$(screen -ls | grep -F "${HOSTNAME%%.*}" | grep -F "${TTY//\//-}")"
-    case "$(echo ${SCREENS:--n} | wc -l)" in
+    # This has to be an echo, not printf.
+    case "$(echo "${SCREENS:--n}" | wc -l)" in
       0)
-        # No screens found - start a new instance, if on a tty.
+        # No screens found - start a new instance if on a tty.
-        [[ "$TTY" == *tty* ]] && sleep 1 && screen
+        [[ "$TTY" == tty* ]] && screen
         ;;
       1)
         # Just one screen - reconnect if it's not dead.
-        if (( $(echo "$SCREENS" | grep "Dead" | wc -l) == 1 )); then
+        if (( $(printf "%s" "$SCREENS" | grep -c -F 'Dead') == 1 )); then
-          echo "Found dead screen for $TTY:"
+          printf "%s:\\n" "Found dead screen for $TTY"
-          echo "$SCREENS" | sed -e 's/^/    /g'
+          printf "%s\\n" "$SCREENS" | sed -e 's/^/    /g'
         else
-          sleep 1
           screen -dr "${TTY//\//-}.${HOSTNAME%%.*}"
         fi
         ;;
       *)
         # Multiple screens - output a list
-        echo "Multiple screens found for $TTY:"
+        printf "%s:\\n" "Multiple screens found for $TTY"
-        echo "$SCREENS" | sed -e 's/^/    /g'
+        printf "%s\\n" "$SCREENS" | sed -e 's/^/    /g'
         ;;
     esac
-    unset SCREENS
   fi
+  unset SCREENS TTY
 }