diff --git a/README.md b/README.md
index e83f1335..3f32367e 100644
--- a/README.md
+++ b/README.md
@@ -4,8 +4,8 @@
-
-
+
+
@@ -142,10 +142,10 @@ PS：
`Shell`用`Bash`的原因是：
- 目前仍然是主流的`Shell`，并且在不同环境基本上都缺省部署了。
-- 在[`Google`的`Shell`风格指南](https://zh-google-styleguide.readthedocs.io/en/latest/google-shell-styleguide/background/)中，明确说明了：`Bash`是**唯一**被允许执行的`shell`脚本语言。
+- 在[`Google`的`Shell`风格指南](https://zh-google-styleguide.readthedocs.io/en/latest/google-shell-styleguide/background/)中，明确说到了：`Bash`是**唯一**被允许执行的`shell`脚本语言。
+- 统一用`Bash`，可以避免差异带来的风险与没有收益的复杂性。
- 有大量的`Shell`实现，`sh`、`bash`、`zsh`、`fish`、`csh`、`tcsh`、`ksh`、`ash`、`dash`……
- 不同的`Shell`有各种差异，深坑勿入。
- - 统一用`Bash`，可以避免差异带来的风险与没有收益的复杂性。
- 个人系统学习过的是`Bash`，比较理解熟悉。
PS: 虽然交互`Shell`个人已经使用`Zsh` + [`oh-my-zsh`](https://ohmyz.sh/)，但在严谨的`Shell`脚本开发时还是使用`Bash`。
diff --git a/bin/a2l b/bin/a2l
index b18c5f7b..01612197 100755
--- a/bin/a2l
+++ b/bin/a2l
@@ -13,7 +13,7 @@ set -eEuo pipefail
# NOTE: DO NOT declare var PROG as readonly in ONE line!
PROG=$(basename -- "$0")
readonly PROG
-readonly PROG_VERSION='2.6.0-dev'
+readonly PROG_VERSION='2.x-dev'
################################################################################
# util functions
diff --git a/bin/ap b/bin/ap
index 3ae5d56e..5d2ffd8d 100755
--- a/bin/ap
+++ b/bin/ap
@@ -15,7 +15,7 @@ set -eEuo pipefail
# NOTE: DO NOT declare var PROG as readonly in ONE line!
PROG=$(basename -- "$0")
readonly PROG
-readonly PROG_VERSION='2.6.0-dev'
+readonly PROG_VERSION='2.x-dev'
################################################################################
# util functions
diff --git a/bin/c b/bin/c
index fde157c1..d844196a 100755
--- a/bin/c
+++ b/bin/c
@@ -29,7 +29,7 @@ set -eEuo pipefail
# NOTE: DO NOT declare var PROG as readonly in ONE line!
PROG=$(basename -- "$0")
readonly PROG
-readonly PROG_VERSION='2.6.0-dev'
+readonly PROG_VERSION='2.x-dev'
################################################################################
# util functions
diff --git a/bin/cp-into-docker-run b/bin/cp-into-docker-run
index 8fff22c3..d4841e67 100755
--- a/bin/cp-into-docker-run
+++ b/bin/cp-into-docker-run
@@ -11,7 +11,7 @@ set -eEuo pipefail
PROG=$(basename -- "$0")
readonly PROG
-readonly PROG_VERSION='2.6.0-dev'
+readonly PROG_VERSION='2.x-dev'
################################################################################
# util functions
diff --git a/bin/find-in-jars b/bin/find-in-jars
index 44e53d31..fc5e198c 100755
--- a/bin/find-in-jars
+++ b/bin/find-in-jars
@@ -34,7 +34,7 @@ set -eEuo pipefail
# NOTE: DO NOT declare var PROG as readonly in ONE line!
PROG=$(basename -- "$0")
readonly PROG
-readonly PROG_VERSION='2.6.0-dev'
+readonly PROG_VERSION='2.x-dev'
################################################################################
# util functions
diff --git a/bin/rp b/bin/rp
index 868a8cfb..d4cce78c 100755
--- a/bin/rp
+++ b/bin/rp
@@ -15,7 +15,7 @@ set -eEuo pipefail
# NOTE: DO NOT declare var PROG as readonly in ONE line!
PROG=$(basename -- "$0")
readonly PROG
-readonly PROG_VERSION='2.6.0-dev'
+readonly PROG_VERSION='2.x-dev'
################################################################################
# util functions
diff --git a/bin/show-busy-java-threads b/bin/show-busy-java-threads
index 7888a7b9..da419b90 100755
--- a/bin/show-busy-java-threads
+++ b/bin/show-busy-java-threads
@@ -28,7 +28,7 @@
# NOTE: DO NOT declare var PROG as readonly in ONE line!
PROG=$(basename -- "$0")
readonly PROG
-readonly PROG_VERSION='2.6.0-dev'
+readonly PROG_VERSION='2.x-dev'
# choosing between $0 and BASH_SOURCE
# https://stackoverflow.com/a/35006505/922688
# How can I get the source directory of a Bash script from within the script itself?
diff --git a/bin/show-duplicate-java-classes b/bin/show-duplicate-java-classes
index 70737791..08365b69 100755
--- a/bin/show-duplicate-java-classes
+++ b/bin/show-duplicate-java-classes
@@ -30,7 +30,7 @@ from zipfile import ZipFile, BadZipfile
################################################################################
# utils functions
################################################################################
-PROG_VERSION = '2.6.0-dev'
+PROG_VERSION = '2.x-dev'
# How to delete line with echo?
# https://unix.stackexchange.com/questions/26576
diff --git a/bin/tcp-connection-state-counter b/bin/tcp-connection-state-counter
index 217b55eb..726b7229 100755
--- a/bin/tcp-connection-state-counter
+++ b/bin/tcp-connection-state-counter
@@ -13,7 +13,7 @@ set -eEuo pipefail
# NOTE: DO NOT declare var PROG as readonly in ONE line!
PROG=$(basename -- "$0")
readonly PROG
-readonly PROG_VERSION='2.6.0-dev'
+readonly PROG_VERSION='2.x-dev'
################################################################################
# util functions
diff --git a/bin/uq b/bin/uq
index 4687c5f7..d05d62b2 100755
--- a/bin/uq
+++ b/bin/uq
@@ -31,7 +31,7 @@ set -eEuo pipefail
# NOTE: DO NOT declare var PROG as readonly in ONE line!
PROG=$(basename -- "$0")
readonly PROG
-readonly PROG_VERSION='2.6.0-dev'
+readonly PROG_VERSION='2.x-dev'
################################################################################
# util functions
diff --git a/bin/xpl b/bin/xpl
index 4a130a39..160fbfb6 100755
--- a/bin/xpl
+++ b/bin/xpl
@@ -28,7 +28,7 @@ set -eEuo pipefail
# NOTE: DO NOT declare var PROG as readonly in ONE line!
PROG=$(basename -- "$0")
readonly PROG
-readonly PROG_VERSION='2.6.0-dev'
+readonly PROG_VERSION='2.x-dev'
################################################################################
# util functions
diff --git a/legacy-bin/cp-svn-url b/legacy-bin/cp-svn-url
index 16b20cce..970147b5 100755
--- a/legacy-bin/cp-svn-url
+++ b/legacy-bin/cp-svn-url
@@ -27,7 +27,7 @@
# NOTE: DO NOT declare var PROG as readonly in ONE line!
PROG="$(basename -- "$0")"
-readonly PROG_VERSION='2.6.0-dev'
+readonly PROG_VERSION='2.x-dev'
usage() {
cat <