`command -v` portability

The "which" utility is not guaranteed to be installed, and if it is, its behavior is not portable.

Conversely, the "command -v" shell builtin is required to exist in all POSIX 2008 compliant shells, and is thus guaranteed to work everywhere.

Examples of open-source shells likely to be installed as /bin/sh on Linux, which implement the 12-year-old standard: ash, bash, busybox, dash, ksh, mksh and zsh.

A side benefit of using the POSIX portable option is that it does not require an external disk executable to be forked. This therefore represents a mild speedup.

scripts/xdg-settings.in

@@ -130,7 +130,7 @@ set_browser_mime()
     fix_local_desktop_file "$1" "$MIME" || return
     mkdir -p "${XDG_DATA_HOME:-$HOME/.local/share}/applications"
     xdg-mime default "$1" "$MIME" || return
-    if [ x"`get_browser_mime`" != x"$1" ]; then
+    if [ x"`get_browser_mime $MIME`" != x"$1" ]; then
         # Put back the original value
         xdg-mime default "$orig" "$MIME"
         exit_failure_operation_failed
@@ -203,7 +203,13 @@ resolve_kde_browser_desktop()
 
 read_kde_browser()
 {
-    read_kde_config kdeglobals General BrowserApplication
+    ret=`read_kde_config kdeglobals General BrowserApplication`
+    if [ -z "$ret" ]; then
+        # since Plasma >= 5.19
+        ret=`get_browser_mime "x-scheme-handler/http"`
+    fi
+    
+    echo $ret
 }
 
 get_browser_kde()
@@ -252,7 +258,13 @@ check_browser_kde()
 
 set_browser_kde()
 {
-    set_browser_mime "$1" || return
+    # Set the default browser.
+    for protocol in http https; do
+        set_browser_mime "$1" "x-scheme-handler/$protocol" || return
+    done
+
+    # Plasma < 5.19
+    set_browser_mime "$1" "text/html" || return
     if [ x"${KDE_SESSION_VERSION}" = x"5" ]; then
         kwriteconfig5 --file kdeglobals --group General --key BrowserApplication "$1"
     else