[pager] Improve pager search

CHANGELOG.md

@@ -1,5 +1,13 @@
 ## Changelog
 
+### 12.88.1
+
+* `[pager]` Improved pager search
+* `[fmtutil]` Code refactoring
+* `[fmtutil/table]` Code refactoring
+* `[pager]` Fixed build tags
+* `[terminal/tty]` Fixed build tags
+
 ### 12.88.0
 
 * `[pager]` Added new package for pager (`less`/`more`) setup

ek.go

@@ -20,7 +20,7 @@ import (
 // ////////////////////////////////////////////////////////////////////////////////// //
 
 // VERSION is current ek package version
-const VERSION = "12.88.0"
+const VERSION = "12.88.1"
 
 // ////////////////////////////////////////////////////////////////////////////////// //
 

pager/pager_posix.go

@@ -20,11 +20,6 @@ import (
 
 // ////////////////////////////////////////////////////////////////////////////////// //
 
-// DEFAULT is default pager command
-const DEFAULT = "more"
-
-// ////////////////////////////////////////////////////////////////////////////////// //
-
 var pagerCmd *exec.Cmd
 var pagerOut *os.File
 
@@ -33,7 +28,15 @@ var stderr *os.File
 
 // ////////////////////////////////////////////////////////////////////////////////// //
 
-var ErrAlreadySet = errors.New("Pager already set")
+var binLess = "less"
+var binMore = "more"
+
+// ////////////////////////////////////////////////////////////////////////////////// //
+
+var (
+	ErrAlreadySet = errors.New("Pager already set")
+	ErrNoPager    = errors.New("There is no pager on the system")
+)
 
 // ////////////////////////////////////////////////////////////////////////////////// //
 
@@ -46,6 +49,10 @@ func Setup(pager string) error {
 
 	pagerCmd = getPagerCommand(pager)
 
+	if pagerCmd == nil {
+		return ErrNoPager
+	}
+
 	pagerCmd.Stdout, stdout = os.Stdout, os.Stdout
 	pagerCmd.Stderr, stderr = os.Stderr, os.Stderr
 
@@ -86,7 +93,11 @@ func getPagerCommand(pager string) *exec.Cmd {
 	}
 
 	if pager == "" {
-		pager = DEFAULT
+		pager = findPager()
+	}
+
+	if pager == "" {
+		return nil
 	}
 
 	if strings.Contains(pager, " ") {
@@ -96,3 +107,32 @@ func getPagerCommand(pager string) *exec.Cmd {
 
 	return exec.Command(pager)
 }
+
+// findPager tries to find pager an it options
+func findPager() string {
+	_, err := exec.LookPath(binMore)
+
+	if err == nil {
+		moreOpts := os.Getenv("MORE")
+
+		if moreOpts != "" {
+			return "more " + moreOpts
+		}
+
+		return "more"
+	}
+
+	_, err = exec.LookPath(binLess)
+
+	if err == nil {
+		lessOpts := os.Getenv("LESS")
+
+		if lessOpts != "" {
+			return "less " + lessOpts
+		}
+
+		return "less -R"
+	}
+
+	return ""
+}

pager/pager_test.go

@@ -32,24 +32,50 @@ func (s *PagerSuite) TearDownSuite(c *C) {
 
 func (s *PagerSuite) TestPager(c *C) {
 	c.Assert(Setup("cat"), IsNil)
-	c.Assert(Setup("cat"), NotNil)
+	c.Assert(Setup("cat"), DeepEquals, ErrAlreadySet)
 
 	Complete()
 
 	c.Assert(pagerCmd, IsNil)
 	c.Assert(pagerOut, IsNil)
+
+	os.Setenv("PAGER", "")
+
+	binMore = "_unknown_"
+	binLess = "_unknown_"
+
+	c.Assert(Setup(""), DeepEquals, ErrNoPager)
 }
 
 func (s *PagerSuite) TestPagerSearch(c *C) {
 	os.Setenv("PAGER", "")
+	os.Setenv("LESS", "")
+	os.Setenv("MORE", "")
 
 	cmd := getPagerCommand("cat")
 	c.Assert(cmd.Args, DeepEquals, []string{"cat"})
 
+	binMore = "echo"
+	binLess = "echo"
+
 	cmd = getPagerCommand("")
 	c.Assert(cmd.Args, DeepEquals, []string{"more"})
 
-	os.Setenv("PAGER", "less -MQR")
+	os.Setenv("MORE", "-l -s")
+
 	cmd = getPagerCommand("")
-	c.Assert(cmd.Args, DeepEquals, []string{"less", "-MQR"})
+	c.Assert(cmd.Args, DeepEquals, []string{"more", "-l", "-s"})
+
+	binMore = "_unknown_"
+
+	cmd = getPagerCommand("")
+	c.Assert(cmd.Args, DeepEquals, []string{"less", "-R"})
+
+	os.Setenv("LESS", "-MRQ")
+
+	cmd = getPagerCommand("")
+	c.Assert(cmd.Args, DeepEquals, []string{"less", "-MRQ"})
+
+	binMore = "more"
+	binLess = "less"
 }