* Some utility functions to make performing substitutions in text

files easier.  Examples:

    substitute inputFile outputFile \
      --replace "@bindir@" "$out/bin" \
      --replace "@gcc@" "$GCC/bin/gcc"

    substitute inputFile outputFile --subst-var out

      (this is sugar for --replace "@out@" "$out")

    substituteInPlace file --replace a b

      (input and output are both `file'; the execute bit is preserved)
  

svn path=/nixpkgs/trunk/; revision=2239

pkgs/build-support/substitute/substitute.sh

@@ -0,0 +1,39 @@
+substitute() {
+    input=$1
+    output=$2
+
+    params=("$@")
+
+    sedArgs=()
+    
+    for ((n = 2; n < ${#params[*]}; n += 1)); do
+        p=${params[$n]}
+
+        if test "$p" = "--replace"; then
+            pattern=${params[$((n + 1))]}
+            replacement=${params[$((n + 2))]}
+            n=$((n + 2))
+            sedArgs=("${sedArgs[@]}" "-e" "s^$pattern^$replacement^g")
+        fi
+
+        if test "$p" = "--subst-var"; then
+            varName=${params[$((n + 1))]}
+            n=$((n + 1))
+            sedArgs=("${sedArgs[@]}" "-e" "s^@${varName}@^${!varName}^g")
+        fi
+
+    done
+
+    sed "${sedArgs[@]}" < "$input" > "$output".tmp
+    if test -x "$output"; then
+        chmod +x "$output".tmp
+    fi
+    mv -f "$output".tmp "$output"
+}
+
+
+substituteInPlace() {
+    fileName="$1"
+    shift
+    substitute "$fileName" "$fileName" "$@"
+}