lib.sh: Move warning code to own function.

[config/dotfiles.git] / lib.sh

diff --git a/lib.sh b/lib.sh
index 582e1cffe66b1f440dcec0744c08f336fffeb8ea..6cd3d2f8d79adf7cb662ae6347fd394c8966e172 100644 (file)
--- a/lib.sh
+++ b/lib.sh
@@ -11,6 +11,28 @@ unset LS_COLORS
 m4=`which m4`
 
 
+# Check if the given program is installed. Returns 0 if it exists, 1
+# otherwise; so it can be used in if.
+installed() {
+    which $1 | grep -E '^/' > /dev/null
+}
+
+# Prints the current OS. Supported are Debian (debian), Gentoo (gentoo) and
+# Mac OS X (darwin) at the moment. If an unsupported OS is used an error is
+# printed.
+os() {
+    if [ -f /etc/debian_version ]; then
+        echo debian
+    elif [ -f /etc/gentoo-release ]; then
+        echo gentoo
+    elif [ x`uname` = xDarwin ]; then
+        echo darwin
+    else
+        echo unsupported OS! >&2
+        return 1
+    fi
+}
+
 # Creates a symbolic link for file $1 in dirname of $2 with name of basenmae
 # $2.
 #
@@ -50,26 +72,41 @@ link() {
     unset pwd base source target
 }
 
+# Write a warning to $1 to make clear it should not be modified. $2 is the
+# source for the generated file.
+setup_warning() {
+    echo "###################################" > $1
+    echo "# WARNING! DO NOT EDIT THIS FILE! #" >> $1
+    echo "###################################" >> $1
+    echo >> $1
+    echo "# It was generated from $2 on `date`." >> $1
+    echo >> $1
+}
+
 # m4 wrapper which uses $1.m4 as template file, feeds it to m4 and writes it
 # to $1 with a warning at the beginning to not edit the generated file.
 #
 # All arguments (except the first which is the filename) are passed to m4.
+#
+# The following macros are defined: IF and FI. Example:
+#     IF(OS, debian)
+#         ...
+#     FI
 m4() {
     # First argument is file name.
     file=$1
     shift
 
-    # Write a warning to the generated file.
-    echo "###################################" > $file
-    echo "# WARNING! DO NOT EDIT THIS FILE! #" >> $file
-    echo "###################################" >> $file
-    echo >> $file
-    echo "# It was generated from $file.m4 on `date`." >> $file
-    echo >> $file
+    # Write a warning to the generated file to not edit it.
+    setup_warning $file $file.m4
 
     # Process $1.m4 with m4 using the given options.
     echo "m4(): generating '$file' from '$file.m4' with options '$*'"
-    $m4 $* $file.m4 >> $file
+    # Add useful macros.
+    (echo "define(\`IF', \`ifelse(\`\$1', \`\$2',dnl')dnl
+define(\`FI', \`)dnl')dnl";
+        # Run the file (and the default macros) through m4.
+        cat $file.m4) | $m4 "$@" >> $file
 
     unset file
 }