diff --git a/tools/common.sh b/tools/common.sh
new file mode 100644
index 0000000000000000000000000000000000000000..74870d03496ae3183c2d2da66bdcb4adbda33860
--- /dev/null
+++ b/tools/common.sh
@@ -0,0 +1,17 @@
+VER=2
+if [ "$1" = -3 ]; then
+    VER=3
+    shift
+fi
+
+if [ -z "${PYTHON}" ]; then
+    which python >/dev/null 2>&1 && PYTHON=$(which python)
+    which python$VER >/dev/null 2>&1 && PYTHON=$(which python$VER)
+    if [ $VER -eq 2 ]; then
+        which python2.7 >/dev/null 2>&1 && PYTHON=$(which python2.7)
+    else
+        which python3.4 >/dev/null 2>&1 && PYTHON=$(which python3.4)
+        which python3.5 >/dev/null 2>&1 && PYTHON=$(which python3.5)
+        which python3.6 >/dev/null 2>&1 && PYTHON=$(which python3.6)
+    fi
+fi
diff --git a/tools/local_install.sh b/tools/local_install.sh
index 34d3b97f3c7672c9a402cf189150f30c3ee26de6..f723b47039d727238864ab63454b9cbb8dbb22af 100755
--- a/tools/local_install.sh
+++ b/tools/local_install.sh
@@ -1,23 +1,7 @@
 #!/bin/sh
 set -e
 
-VER=2
-if [ "$1" = -3 ]; then
-    VER=3
-    shift
-fi
-
-if [ -z "${PYTHON}" ]; then
-    which python >/dev/null 2>&1 && PYTHON=$(which python)
-    which python$VER >/dev/null 2>&1 && PYTHON=$(which python$VER)
-    if [ $VER -eq 2 ]; then
-        which python2.7 >/dev/null 2>&1 && PYTHON=$(which python2.7)
-    else
-        which python3.4 >/dev/null 2>&1 && PYTHON=$(which python3.4)
-        which python3.5 >/dev/null 2>&1 && PYTHON=$(which python3.5)
-        which python3.6 >/dev/null 2>&1 && PYTHON=$(which python3.6)
-    fi
-fi
+. "$(dirname $0)/common.sh"
 
 $PYTHON "$(dirname $0)/stale_pyc.py"
 
diff --git a/tools/local_run.sh b/tools/local_run.sh
index 5fb19dd6407a91d749437d302564536634979ce1..12d245fec8cd59324b1e7b5a983e282b82e71c0b 100755
--- a/tools/local_run.sh
+++ b/tools/local_run.sh
@@ -1,23 +1,7 @@
 #!/bin/sh
 set -e
 
-VER=2
-if [ "$1" = -3 ]; then
-    VER=3
-    shift
-fi
-
-if [ -z "${PYTHON}" ]; then
-    which python >/dev/null 2>&1 && PYTHON=$(which python)
-    which python$VER >/dev/null 2>&1 && PYTHON=$(which python$VER)
-    if [ $VER -eq 2 ]; then
-        which python2.7 >/dev/null 2>&1 && PYTHON=$(which python2.7)
-    else
-        which python3.4 >/dev/null 2>&1 && PYTHON=$(which python3.4)
-        which python3.5 >/dev/null 2>&1 && PYTHON=$(which python3.5)
-        which python3.6 >/dev/null 2>&1 && PYTHON=$(which python3.6)
-    fi
-fi
+. "$(dirname $0)/common.sh"
 
 $PYTHON "$(dirname $0)/stale_pyc.py"
 
diff --git a/tools/make_man.sh b/tools/make_man.sh
index ede9a4980cf3b69740ad800af612040a4d1871ea..f343cf31b8ad742f2c5595fc6ae9f3802a963fc5 100755
--- a/tools/make_man.sh
+++ b/tools/make_man.sh
@@ -3,23 +3,7 @@
 # stop on failure
 set -e
 
-VER=2
-if [ "$1" = -3 ]; then
-    VER=3
-    shift
-fi
-
-if [ -z "${PYTHON}" ]; then
-    which python >/dev/null 2>&1 && PYTHON=$(which python)
-    which python$VER >/dev/null 2>&1 && PYTHON=$(which python$VER)
-    if [ $VER -eq 2 ]; then
-        which python2.7 >/dev/null 2>&1 && PYTHON=$(which python2.7)
-    else
-        which python3.4 >/dev/null 2>&1 && PYTHON=$(which python3.4)
-        which python3.5 >/dev/null 2>&1 && PYTHON=$(which python3.5)
-        which python3.6 >/dev/null 2>&1 && PYTHON=$(which python3.6)
-    fi
-fi
+. "$(dirname $0)/common.sh"
 
 # Use C local to avoid local dates in headers
 export LANG=en_US.utf8
diff --git a/tools/run_tests.sh b/tools/run_tests.sh
index 2dac9bc8e235e46b9600f6e492d62f4d768fdd69..6964296f26f35135e16139a470aadae80715b6d2 100755
--- a/tools/run_tests.sh
+++ b/tools/run_tests.sh
@@ -10,12 +10,19 @@
 # stop on failure
 set -e
 
-VER=2
-if [ "$1" = -3 ]; then
-	VER=3
-	shift
+. "$(dirname $0)/common.sh"
+
+if [ -z "${PYTHON}" ]; then
+    echo "Python required"
+    exit 1
 fi
 
+if ! $PYTHON -c "import nose" 2>/dev/null; then
+    echo "python-nose required"
+    exit 1
+fi
+
+
 # path to sources
 WEBOOB_DIR=$(cd $(dirname $0)/.. && pwd -P)
 
@@ -61,30 +68,6 @@ else
     WEBOOB_CI_TARGET=""
 fi
 
-
-# find executables
-if [ -z "${PYTHON}" ]; then
-    which python >/dev/null 2>&1 && PYTHON=$(which python)
-    which python$VER >/dev/null 2>&1 && PYTHON=$(which python$VER)
-    if [ $VER -eq 2 ]; then
-        which python2.7 >/dev/null 2>&1 && PYTHON=$(which python2.7)
-    else
-        which python3.4 >/dev/null 2>&1 && PYTHON=$(which python3.4)
-        which python3.5 >/dev/null 2>&1 && PYTHON=$(which python3.5)
-        which python3.6 >/dev/null 2>&1 && PYTHON=$(which python3.6)
-    fi
-fi
-
-if [ -z "${PYTHON}" ]; then
-    echo "Python required"
-    exit 1
-fi
-
-if ! $PYTHON -c "import nose" 2>/dev/null; then
-    echo "python-nose required"
-    exit 1
-fi
-
 # do not allow undefined variables anymore
 set -u
 if [ -f "${WEBOOB_BACKENDS}" ]; then
diff --git a/tools/weboob_lint.sh b/tools/weboob_lint.sh
index 1628b12e74bfc32f6958e4a173a3697e8fef728e..0aecba52d792aa7d46c8544822c00a5c47ebf115 100755
--- a/tools/weboob_lint.sh
+++ b/tools/weboob_lint.sh
@@ -3,23 +3,7 @@
 # stop on failure
 set -e
 
-VER=2
-if [ "$1" = -3 ]; then
-    VER=3
-    shift
-fi
-
-if [ -z "${PYTHON}" ]; then
-    which python >/dev/null 2>&1 && PYTHON=$(which python)
-    which python$VER >/dev/null 2>&1 && PYTHON=$(which python$VER)
-    if [ $VER -eq 2 ]; then
-        which python2.7 >/dev/null 2>&1 && PYTHON=$(which python2.7)
-    else
-        which python3.4 >/dev/null 2>&1 && PYTHON=$(which python3.4)
-        which python3.5 >/dev/null 2>&1 && PYTHON=$(which python3.5)
-        which python3.6 >/dev/null 2>&1 && PYTHON=$(which python3.6)
-    fi
-fi
+. "$(dirname $0)/common.sh"
 
 [ -z "${TMPDIR}" ] && TMPDIR="/tmp"