bootstrap-conda: Rewrite using fewer redirects

bootstrap-conda

@@ -47,36 +47,49 @@ for PKG_BASE in $(./sage --package list --has-file distros/conda.txt); do
     fi
 done
 echo >&2 $0:$LINENO: generate conda enviroment files
-echo "name: sage-build" >  environment.yml
-echo "channels:"        >> environment.yml
-echo "  - conda-forge"  >> environment.yml
-echo "  - nodefaults"   >> environment.yml
-echo "dependencies:"    >> environment.yml
-for pkg in $SYSTEM_PACKAGES; do
-    echo "  - $pkg" >> environment.yml
-done
-echo "  # Packages needed for ./bootstrap" >> environment.yml
-for pkg in $BOOTSTRAP_PACKAGES; do
-    echo "  - $pkg" >> environment.yml
-done
-sed 's/name: sage-build/name: sage/' environment.yml > src/environment.yml
-echo "  # Additional packages providing all dependencies for the Sage library" >> src/environment.yml
-for pkg in $SAGELIB_SYSTEM_PACKAGES; do
-    echo "  - $pkg" >> src/environment.yml
-done
-sed 's/name: sage/name: sage-dev/' src/environment.yml > src/environment-dev.yml
-echo "  # Additional dev tools" >> src/environment-dev.yml
-for pkg in $DEVELOP_SYSTEM_PACKAGES; do
-    echo "  - $pkg" >> src/environment-dev.yml
-done
+(
+    echo "name: sage-build"
+    echo "channels:"
+    echo "  - conda-forge"
+    echo "  - nodefaults"
+    echo "dependencies:"
+    for pkg in $SYSTEM_PACKAGES; do
+        echo "  - $pkg"
+    done
+    echo "  # Packages needed for ./bootstrap"
+    for pkg in $BOOTSTRAP_PACKAGES; do
+        echo "  - $pkg"
+    done
+) > environment.yml
 
-cp environment.yml environment-optional.yml
-    echo "  # optional packages" >> environment-optional.yml
-for pkg in $OPTIONAL_SYSTEM_PACKAGES; do
-    echo "  - $pkg" >> environment-optional.yml
+(
+    sed 's/name: sage-build/name: sage/' environment.yml
+    echo "  # Additional packages providing all dependencies for the Sage library"
+    for pkg in $SAGELIB_SYSTEM_PACKAGES; do
+        echo "  - $pkg"
     done
-cp src/environment.yml src/environment-optional.yml
-    echo "  # optional packages" >> src/environment-optional.yml
-for pkg in $OPTIONAL_SYSTEM_PACKAGES $SAGELIB_OPTIONAL_SYSTEM_PACKAGES; do
-    echo "  - $pkg" >> src/environment-optional.yml
-done
+) > src/environment.yml
+
+(
+    sed 's/name: sage/name: sage-dev/' src/environment.yml
+    echo "  # Additional dev tools"
+    for pkg in $DEVELOP_SYSTEM_PACKAGES; do
+        echo "  - $pkg"
+    done
+) > src/environment-dev.yml
+
+(
+    cat environment.yml
+    echo "  # optional packages"
+    for pkg in $OPTIONAL_SYSTEM_PACKAGES; do
+        echo "  - $pkg"
+    done
+) > environment-optional.yml
+
+(
+    cat src/environment.yml
+    echo "  # optional packages"
+    for pkg in $OPTIONAL_SYSTEM_PACKAGES $SAGELIB_OPTIONAL_SYSTEM_PACKAGES; do
+        echo "  - $pkg"
+    done
+) > src/environment-optional.yml