Fix/batch cash bc cmd (#162)

* fix: add check for batch_cash script

* fix: add comment

* fix: complete documentation

docs/tutorial-upgrade-to-v2.1.2.md

@@ -12,6 +12,8 @@ We provide a bash script to facilitate these burdensome operations, and you can
 
 Note that the script will skip cashing cheques whose cashable amount is less than estimated gas fee.
 
+
+
 ```shell
 # When API endpoint is 127.0.0.1:5001, which is the default one
 $ curl -s https://raw.githubusercontent.com/bittorrent/go-btfs/master/scripts/batch_cash.sh | bash -s 127.0.0.1:5001
@@ -20,6 +22,26 @@ $ curl -s https://raw.githubusercontent.com/bittorrent/go-btfs/master/scripts/ba
 $ curl -s https://raw.githubusercontent.com/bittorrent/go-btfs/master/scripts/batch_cash.sh | bash -s <your-api-host>
 ```
 
+Before running this script, please confirm that 'curl' and 'bc' tools are installed on your system. 
+If not, you can install them through the system's corresponding package management tools, for example:
+
+```shell
+# on centos
+$ sudo yum install -y curl
+$ sudo yum install -y bc
+
+# on ubuntu
+$ sudo apt install curl
+$ sudo apt install bc
+
+# on macos
+$ brew install curl
+$ brew install bc
+```
+
+If your system is windows, you may need to install 'git-bash' and the corresponding 'bc' tool to run this script. 
+If you have difficulty installing these tools, you can cash cheques and withdraw balance manually via commands or dashboard, just a little more tedious.
+
 The scripts will prompts "Success, all tasks completed!" if everything gose well.
 You can run the script again if it failed due to occasional reasons, weak network for example.
 

scripts/batch_cash.sh

@@ -15,6 +15,14 @@ wait_seconds=15
 # check curl
 if ! [ -x "$(command -v curl)" ]; then
     echo "curl is not found"
+    echo "for details, please refer to this document: https://github.com/bittorrent/go-btfs/blob/master/docs/tutorial-upgrade-to-v2.1.2.md"
+    exit 1
+fi
+
+# check bc
+if ! [ -x "$(command -v bc)" ]; then
+    echo "bc is not found"
+    echo "for details, please refer to this document: https://github.com/bittorrent/go-btfs/blob/master/docs/tutorial-upgrade-to-v2.1.2.md"
     exit 1
 fi