added -k parameter to sort by columns

Separator and fixed #3

Makefile

@@ -26,7 +26,7 @@ GID     = 0
 BRANCH  = $(shell git describe --all | cut -d/ -f2)
 COMMIT  = $(shell git rev-parse --short=8 HEAD)
 BUILD   = $(shell date +%Y.%m.%d.%H%M%S) 
-VERSION:= $(if $(filter $(BRANCH), development),$(version)-$(BRANCH)-$(COMMIT)-$(BUILD))
+VERSION:= $(if $(filter $(BRANCH), development),$(version)-$(BRANCH)-$(COMMIT)-$(BUILD),$(version))
 
 
 all: $(tool).1 cmd/$(tool).go buildlocal
@@ -45,6 +45,7 @@ buildlocal:
 
 release:
 	./mkrel.sh $(tool) $(version)
+	gh release create $(version) --generate-notes releases/*
 
 install: buildlocal
 	install -d -o $(UID) -g $(GID) $(PREFIX)/bin

README.md

@@ -20,13 +20,13 @@ But you're only interested in the  NAME and STATUS columns. Here's how
 to do this with tablizer:
 
 ```
-% kubectl get pods | ./tablizer 
+% kubectl get pods | tablizer 
 NAME(1)                      READY(2) STATUS(3)  RESTARTS(4)    AGE(5)
 repldepl-7bcd8d5b64-7zq4l    1/1      Running    1 (69m ago)    5h26m
 repldepl-7bcd8d5b64-m48n8    1/1      Running    1 (69m ago)    5h26m
 repldepl-7bcd8d5b64-q2bf4    1/1      Running    1 (69m ago)    5h26m
 
-% kubectl get pods | ./tablizer -c 1,3
+% kubectl get pods | tablizer -c 1,3
 NAME(1)                      STATUS(3)
 repldepl-7bcd8d5b64-7zq4l    Running
 repldepl-7bcd8d5b64-m48n8    Running
@@ -34,27 +34,28 @@ repldepl-7bcd8d5b64-q2bf4    Running
 ```
 
 Another use case is when the tabular  output is so wide that lines are
-being broken and  the whole output is completely distorted.  In such a
+being broken and the whole output  is completely distorted.  In such a
-case you can use the `-x` flag to get an output similar to `\x` in `psql`:
+case you can use the `-o extended  | -X` flag to get an output similar
+to `\x` in `psql`:
 
 ```
-% kubectl get pods | ./tablizer -x    
+% kubectl get pods | tablizer -X
-    NAME: repldepl-7bcd8d5b64-7zq4l  
+    NAME: repldepl-7bcd8d5b64-7zq4l
-   READY: 1/1    
+   READY: 1/1
-  STATUS: Running  
+  STATUS: Running
-RESTARTS: 1 (71m ago)  
+RESTARTS: 1 (71m ago)
      AGE: 5h28m
 
-    NAME: repldepl-7bcd8d5b64-m48n8  
+    NAME: repldepl-7bcd8d5b64-m48n8
-   READY: 1/1    
+   READY: 1/1
-  STATUS: Running  
+  STATUS: Running
-RESTARTS: 1 (71m ago)  
+RESTARTS: 1 (71m ago)
      AGE: 5h28m
 
-    NAME: repldepl-7bcd8d5b64-q2bf4  
+    NAME: repldepl-7bcd8d5b64-q2bf4
-   READY: 1/1    
+   READY: 1/1
-  STATUS: Running  
+  STATUS: Running
-RESTARTS: 1 (71m ago)  
+RESTARTS: 1 (71m ago)
      AGE: 5h28m
 ```
 
@@ -63,11 +64,12 @@ Tablize can read one or more files or - if none specified - from STDIN.
 You can also specify a regex pattern to reduce the output:
 
 ```
-% kubectl get pods | ./tablizer q2bf4
+% kubectl get pods | tablizer q2bf4
 NAME(1)                      READY(2) STATUS(3)  RESTARTS(4)    AGE(5)
 repldepl-7bcd8d5b64-q2bf4    1/1      Running    1 (69m ago)    5h26m
 ```
 
+There are more output modes like org-mode (orgtbl) and markdown.
 
 ## Installation
 
@@ -106,6 +108,10 @@ https://github.com/TLINDEN/tablizer/blob/main/tablizer.pod
 Or if you cloned  the repository you can read it  this way (perl needs
 to be installed though): `perldoc tablizer.pod`.
 
+If you have the binary installed, you  can also read the man page with
+this command:
+
+    tablizer --man
 
 ## Getting help
 

cmd/root.go

@@ -18,33 +18,31 @@ package cmd
 
 import (
 	"bytes"
-	"github.com/tlinden/tablizer/lib"
 	"fmt"
 	"github.com/spf13/cobra"
+	"github.com/tlinden/tablizer/lib"
 	"log"
 	"os"
 	"os/exec"
 )
 
-var helpCmd = &cobra.Command{
+var ShowManual = false
-	Use:   "help",
-	Short: "Show documentation",
-	Run: func(cmd *cobra.Command, args []string) {
-		man := exec.Command("less", "-")
 
-		var b bytes.Buffer
+func man() {
-		b.Write([]byte(manpage))
+	man := exec.Command("less", "-")
 
-		man.Stdout = os.Stdout
+	var b bytes.Buffer
-		man.Stdin = &b
+	b.Write([]byte(manpage))
-		man.Stderr = os.Stderr
 
-		err := man.Run()
+	man.Stdout = os.Stdout
+	man.Stdin = &b
+	man.Stderr = os.Stderr
 
-		if err != nil {
+	err := man.Run()
-			log.Fatal(err)
+
-		}
+	if err != nil {
-	},
+		log.Fatal(err)
+	}
 }
 
 var rootCmd = &cobra.Command{
@@ -57,6 +55,11 @@ var rootCmd = &cobra.Command{
 			return nil
 		}
 
+		if ShowManual {
+			man()
+			return nil
+		}
+
 		err := lib.PrepareColumns()
 		if err != nil {
 			return err
@@ -81,9 +84,13 @@ func Execute() {
 func init() {
 	rootCmd.PersistentFlags().BoolVarP(&lib.Debug, "debug", "d", false, "Enable debugging")
 	rootCmd.PersistentFlags().BoolVarP(&lib.NoNumbering, "no-numbering", "n", false, "Disable header numbering")
-	rootCmd.PersistentFlags().BoolVarP(&lib.ShowVersion, "version", "v", false, "Print program version")
+	rootCmd.PersistentFlags().BoolVarP(&lib.NoColor, "no-color", "N", false, "Disable pattern highlighting")
-	rootCmd.PersistentFlags().StringVarP(&lib.Separator, "separator", "s", "", "Custom field separator")
+	rootCmd.PersistentFlags().BoolVarP(&lib.ShowVersion, "version", "V", false, "Print program version")
+	rootCmd.PersistentFlags().BoolVarP(&lib.InvertMatch, "invert-match", "v", false, "select non-matching rows")
+	rootCmd.PersistentFlags().BoolVarP(&ShowManual, "man", "m", false, "Display manual page")
+	rootCmd.PersistentFlags().StringVarP(&lib.Separator, "separator", "s", lib.DefaultSeparator, "Custom field separator")
 	rootCmd.PersistentFlags().StringVarP(&lib.Columns, "columns", "c", "", "Only show the speficied columns (separated by ,)")
+	rootCmd.PersistentFlags().IntVarP(&lib.SortByColumn, "sort-by", "k", 0, "Sort by column (default: 1)")
 
 	// output flags, only 1 allowed, hidden, since just short cuts
 	rootCmd.PersistentFlags().BoolVarP(&lib.OutflagExtended, "extended", "X", false, "Enable extended output")
@@ -98,11 +105,4 @@ func init() {
 
 	// same thing but more common, takes precedence over above group
 	rootCmd.PersistentFlags().StringVarP(&lib.OutputMode, "output", "o", "", "Output mode - one of: orgtbl, markdown, extended, shell, ascii(default)")
-
-	rootCmd.AddCommand(helpCmd)
-
-	rootCmd.SetHelpCommand(&cobra.Command{
-		Use:    "no-help",
-		Hidden: true,
-	})
 }

cmd/tablizer.go

@@ -11,21 +11,25 @@ SYNOPSIS
           -c, --columns string     Only show the speficied columns (separated by ,)
           -d, --debug              Enable debugging
           -h, --help               help for tablizer
+          -v, --invert-match       select non-matching rows
+          -m, --man                Display manual page
           -n, --no-numbering       Disable header numbering
+          -N, --no-color           Disable pattern highlighting
           -o, --output string      Output mode - one of: orgtbl, markdown, extended, ascii(default)
           -X, --extended           Enable extended output
           -M, --markdown           Enable markdown table output
           -O, --orgtbl             Enable org-mode table output
           -s, --separator string   Custom field separator
+          -k, --sort-by int        Sort by column (default: 1)
           -v, --version            Print program version
 
 DESCRIPTION
     Many programs generate tabular output. But sometimes you need to
     post-process these tables, you may need to remove one or more columns or
-    you may want to filter for some pattern or you may need the output in
+    you may want to filter for some pattern (See PATTERNS) or you may need
-    another program and need to parse it somehow. Standard unix tools such
+    the output in another program and need to parse it somehow. Standard
-    as awk(1), grep(1) or column(1) may help, but sometimes it's a tedious
+    unix tools such as awk(1), grep(1) or column(1) may help, but sometimes
-    business.
+    it's a tedious business.
 
     Let's take the output of the tool kubectl. It contains cells with
     withespace and they do not separate columns by TAB characters. This is
@@ -38,7 +42,8 @@ DESCRIPTION
 
     Without any options it reads its input from "STDIN", but you can also
     specify a file as a parameter. If you want to reduce the output by some
-    regular expression, just specify it as its first parameters. Hence:
+    regular expression, just specify it as its first parameter. You may also
+    use the -v option to exclude all rows which match the pattern. Hence:
 
        # read from STDIN
        kubectl get pods | tablizer
@@ -67,9 +72,40 @@ DESCRIPTION
 
     The numbering can be suppressed by using the -n option.
 
+    By default, if a pattern has been speficied, matches will be
+    highlighted. You can disable this behavior with the -N option.
+
+    Use the -k option to specify by which column to sort the tabular data
+    (as in GNU sort(1)). The default sort column is the first one. To
+    disable sorting at all, supply 0 (Zero) to -k.
+
     Finally the -d option enables debugging output which is mostly usefull
     for the developer.
 
+  PATTERNS
+    You can reduce the rows being displayed by using a regular expression
+    pattern. The regexp is PCRE compatible, refer to the syntax cheat sheet
+    here: <https://github.com/google/re2/wiki/Syntax>. If you want to read a
+    more comprehensive documentation about the topic and have perl installed
+    you can read it with:
+
+        perldoc perlre
+
+    Or read it online: <https://perldoc.perl.org/perlre>.
+
+    A note on modifiers: the regexp engine used in tablizer uses another
+    modifier syntax:
+
+        (?MODIFIER)
+
+    The most important modifiers are:
+
+    "i" ignore case "m" multiline mode "s" single line mode
+
+    Example for a case insensitve search:
+
+        kubectl get pods -A | tablizer "(?i)account"
+
   OUTPUT MODES
     There might be cases when the tabular output of a program is way too
     large for your current terminal but you still need to see every column.

go.mod

@@ -4,13 +4,15 @@ go 1.18
 
 require (
 	github.com/alecthomas/repr v0.0.0-20180818092828-117648cd9897
+	github.com/gookit/color v1.5.2
 	github.com/olekukonko/tablewriter v0.0.5
 	github.com/spf13/cobra v1.5.0
+	github.com/xo/terminfo v0.0.0-20210125001918-ca9a967f8778
 )
 
 require (
 	github.com/inconshreveable/mousetrap v1.0.0 // indirect
 	github.com/mattn/go-runewidth v0.0.9 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
-	github.com/stretchr/testify v1.8.0 // indirect
+	golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44 // indirect
 )

go.sum

@@ -4,6 +4,8 @@ github.com/cpuguy83/go-md2man/v2 v2.0.2/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46t
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/gookit/color v1.5.2 h1:uLnfXcaFjlrDnQDT+NCBcfhrXqYTx/rcCa6xn01Y8yI=
+github.com/gookit/color v1.5.2/go.mod h1:w8h4bGiHeeBpvQVePTutdbERIUf3oJE5lZ8HM0UgXyg=
 github.com/inconshreveable/mousetrap v1.0.0 h1:Z8tu5sraLXCXIcARxBp/8cbvlwVa7Z1NHg9XEKhtSvM=
 github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=
 github.com/mattn/go-runewidth v0.0.9 h1:Lm995f3rfxdpd6TSmuVCHVb/QhupuXlYr8sCI/QdE+0=
@@ -22,6 +24,10 @@ github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSS
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
+github.com/xo/terminfo v0.0.0-20210125001918-ca9a967f8778 h1:QldyIu/L63oPpyvQmHgvgickp1Yw510KJOqX7H24mg8=
+github.com/xo/terminfo v0.0.0-20210125001918-ca9a967f8778/go.mod h1:2MuV+tbUrU1zIOPMxZ5EncGwgmMJsa+9ucAQZXxsObs=
+golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44 h1:Bli41pIlzTzf3KEY06n+xnzK/BESIg2ze4Pgfh/aI8c=
+golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

lib/common.go

@@ -17,29 +17,73 @@ along with this program. If not, see <http://www.gnu.org/licenses/>.
 
 package lib
 
+import (
+	"github.com/gookit/color"
+	//"github.com/xo/terminfo"
+)
+
 var (
 	// command line flags
-	Debug           bool
+	Debug            bool
-	XtendedOut      bool
+	XtendedOut       bool
-	NoNumbering     bool
+	NoNumbering      bool
-	ShowVersion     bool
+	ShowVersion      bool
-	Columns         string
+	Columns          string
-	UseColumns      []int
+	UseColumns       []int
-	Separator       string
+	DefaultSeparator string = `(\s\s+|\t)`
-	OutflagExtended bool
+	Separator        string = `(\s\s+|\t)`
-	OutflagMarkdown bool
+	OutflagExtended  bool
-	OutflagOrgtable bool
+	OutflagMarkdown  bool
-	OutflagShell    bool
+	OutflagOrgtable  bool
-	OutputMode      string
+	OutflagShell     bool
+	OutputMode       string
+	InvertMatch      bool
+	Pattern          string
+
+	/*
+	 FIXME: make configurable somehow, config file or ENV
+	 see https://github.com/gookit/color will be set by
+	 io.ProcessFiles() according to currently supported
+	 color mode.
+	*/
+	MatchFG string
+	MatchBG string
+	NoColor bool
+
+	// colors to be used per supported color mode
+	Colors = map[color.Level]map[string]string{
+		color.Level16: map[string]string{
+			"bg": "green", "fg": "black",
+		},
+		color.Level256: map[string]string{
+			"bg": "lightGreen", "fg": "black",
+		},
+		color.LevelRgb: map[string]string{
+			// FIXME: maybe use something nicer
+			"bg": "lightGreen", "fg": "black",
+		},
+	}
 
 	// used for validation
 	validOutputmodes = "(orgtbl|markdown|extended|ascii)"
 
 	// main program version
-	Version = "v1.0.4"
+	Version = "v1.0.8"
 
 	// generated  version string, used  by -v contains  lib.Version on
 	//  main  branch,   and  lib.Version-$branch-$lastcommit-$date  on
 	// development branch
 	VERSION string
+
+	// sorting
+	SortByColumn int
 )
+
+// contains a whole parsed table
+type Tabdata struct {
+	maxwidthHeader int      // longest header
+	maxwidthPerCol []int    // max width per column
+	columns        int      // count
+	headers        []string // [ "ID", "NAME", ...]
+	entries        [][]string
+}

lib/helpers.go

@@ -20,6 +20,8 @@ package lib
 import (
 	"errors"
 	"fmt"
+	"github.com/gookit/color"
+	"os"
 	"regexp"
 	"strconv"
 	"strings"
@@ -48,8 +50,62 @@ func PrepareColumns() error {
 	return nil
 }
 
+func numberizeHeaders(data *Tabdata) {
+	// prepare headers: add numbers to headers
+	numberedHeaders := []string{}
+	maxwidth := 0 // start from scratch, so we only look at displayed column widths
+
+	for i, head := range data.headers {
+		headlen := 0
+		if len(Columns) > 0 {
+			// -c specified
+			if !contains(UseColumns, i+1) {
+				// ignore this one
+				continue
+			}
+		}
+		if NoNumbering {
+			numberedHeaders = append(numberedHeaders, head)
+			headlen = len(head)
+		} else {
+			numhead := fmt.Sprintf("%s(%d)", head, i+1)
+			headlen = len(numhead)
+			numberedHeaders = append(numberedHeaders, numhead)
+		}
+
+		if headlen > maxwidth {
+			maxwidth = headlen
+		}
+	}
+	data.headers = numberedHeaders
+	if data.maxwidthHeader != maxwidth && maxwidth > 0 {
+		data.maxwidthHeader = maxwidth
+	}
+}
+
+func reduceColumns(data *Tabdata) {
+	// exclude columns, if any
+	if len(Columns) > 0 {
+		reducedEntries := [][]string{}
+		reducedEntry := []string{}
+		for _, entry := range data.entries {
+			reducedEntry = nil
+			for i, value := range entry {
+				if !contains(UseColumns, i+1) {
+					continue
+				}
+
+				reducedEntry = append(reducedEntry, value)
+			}
+			reducedEntries = append(reducedEntries, reducedEntry)
+		}
+		data.entries = reducedEntries
+	}
+}
+
 func PrepareModeFlags() error {
 	if len(OutputMode) == 0 {
+		// associate short flags like -X with mode selector
 		switch {
 		case OutflagExtended:
 			OutputMode = "extended"
@@ -89,3 +145,21 @@ func trimRow(row []string) []string {
 
 	return fixedrow
 }
+
+func colorizeData(output string) string {
+	if len(Pattern) > 0 && !NoColor && color.IsConsole(os.Stdout) {
+		r := regexp.MustCompile("(" + Pattern + ")")
+		return r.ReplaceAllString(output, "<bg="+MatchBG+";fg="+MatchFG+">$1</>")
+	} else {
+		return output
+	}
+}
+
+func isTerminal(f *os.File) bool {
+	o, _ := f.Stat()
+	if (o.Mode() & os.ModeCharDevice) == os.ModeCharDevice {
+		return true
+	} else {
+		return false
+	}
+}

lib/helpers_test.go

@@ -52,6 +52,7 @@ func TestPrepareColumns(t *testing.T) {
 	}{
 		{"1,2,3", []int{1, 2, 3}, false},
 		{"1,2,", []int{}, true},
+		{"a,b", []int{}, true},
 	}
 
 	for _, tt := range tests {
@@ -71,3 +72,46 @@ func TestPrepareColumns(t *testing.T) {
 		})
 	}
 }
+
+func TestReduceColumns(t *testing.T) {
+	var tests = []struct {
+		expect  [][]string
+		columns []int
+	}{
+		{
+			expect:  [][]string{[]string{"a", "b"}},
+			columns: []int{1, 2},
+		},
+		{
+			expect:  [][]string{[]string{"a", "c"}},
+			columns: []int{1, 3},
+		},
+		{
+			expect:  [][]string{[]string{"a"}},
+			columns: []int{1},
+		},
+		{
+			expect:  [][]string{nil},
+			columns: []int{4},
+		},
+	}
+
+	input := [][]string{[]string{"a", "b", "c"}}
+
+	Columns = "y" // used as a flag with len(Columns)...
+
+	for _, tt := range tests {
+		testname := fmt.Sprintf("reduce-columns-by-%+v", tt.columns)
+		t.Run(testname, func(t *testing.T) {
+			UseColumns = tt.columns
+			data := Tabdata{entries: input}
+			reduceColumns(&data)
+			if !reflect.DeepEqual(data.entries, tt.expect) {
+				t.Errorf("reduceColumns returned invalid data:\ngot: %+v\nexp: %+v", data.entries, tt.expect)
+			}
+		})
+	}
+
+	Columns = "" // reset for other tests
+	UseColumns = nil
+}

lib/io.go

@@ -19,6 +19,7 @@ package lib
 
 import (
 	"errors"
+	"github.com/gookit/color"
 	"io"
 	"os"
 )
@@ -26,6 +27,14 @@ import (
 func ProcessFiles(args []string) error {
 	fds, pattern, err := determineIO(args)
 
+	if !isTerminal(os.Stdout) {
+		color.Disable()
+	} else {
+		level := color.TermColorLevel()
+		MatchFG = Colors[level]["fg"]
+		MatchBG = Colors[level]["bg"]
+	}
+
 	if err != nil {
 		return err
 	}
@@ -52,6 +61,7 @@ func determineIO(args []string) ([]io.Reader, string, error) {
 			// first  one is  not a  file, consider  it as  regexp and
 			// shift arg list
 			pattern = args[0]
+			Pattern = args[0] // FIXME
 			args = args[1:]
 		}
 

lib/parser.go

@@ -27,51 +27,29 @@ import (
 	"strings"
 )
 
-// contains a whole parsed table
-type Tabdata struct {
-	maxwidthHeader int   // longest header
-	maxwidthPerCol []int // max width per column
-	columns        int
-	headerIndices  []map[string]int // [ {beg=>0, end=>17}, ... ]
-	headers        []string         // [ "ID", "NAME", ...]
-	entries        [][]string
-}
-
 /*
-   Parse tabular input. We split the  header (first line) by 2 or more
+   Parse tabular input.
-   spaces, remember the positions of  the header fields. We then split
-   the data (everything after the first line) by those positions. That
-   way we can turn "tabular data" (with fields containing whitespaces)
-   into real tabular data. We re-tabulate our input if you will.
 */
 func parseFile(input io.Reader, pattern string) (Tabdata, error) {
 	data := Tabdata{}
 
 	var scanner *bufio.Scanner
-	var spaces = `\s\s+|$`
-
-	if len(Separator) > 0 {
-		spaces = Separator
-	}
 
 	hadFirst := false
-	spacefinder := regexp.MustCompile(spaces)
+	separate := regexp.MustCompile(Separator)
-	beg := 0
+	patternR, err := regexp.Compile(pattern)
+	if err != nil {
+		return data, errors.Unwrap(fmt.Errorf("Regexp pattern %s is invalid: %w", pattern, err))
+	}
 
 	scanner = bufio.NewScanner(input)
 
 	for scanner.Scan() {
 		line := strings.TrimSpace(scanner.Text())
-		values := []string{}
+		parts := separate.Split(line, -1)
-
-		patternR, err := regexp.Compile(pattern)
-		if err != nil {
-			return data, errors.Unwrap(fmt.Errorf("Regexp pattern %s is invalid: %w", pattern, err))
-		}
 
 		if !hadFirst {
 			// header processing
-			parts := spacefinder.FindAllStringIndex(line, -1)
 			data.columns = len(parts)
 			// if Debug {
 			// 	fmt.Println(parts)
@@ -83,30 +61,14 @@ func parseFile(input io.Reader, pattern string) (Tabdata, error) {
 				// 	fmt.Printf("Part: <%s>\n", string(line[beg:part[0]]))
 				//}
 
-				// current field
-				head := string(line[beg:part[0]])
-
-				// register begin and end of field within line
-				indices := make(map[string]int)
-				indices["beg"] = beg
-				if part[0] == part[1] {
-					indices["end"] = 0
-				} else {
-					indices["end"] = part[1] - 1
-				}
-
 				// register widest header field
-				headerlen := len(head)
+				headerlen := len(part)
 				if headerlen > data.maxwidthHeader {
 					data.maxwidthHeader = headerlen
 				}
 
 				// register fields data
-				data.headerIndices = append(data.headerIndices, indices)
+				data.headers = append(data.headers, strings.TrimSpace(part))
-				data.headers = append(data.headers, head)
-
-				// end of current field == begin of next one
-				beg = part[1]
 
 				// done
 				hadFirst = true
@@ -114,22 +76,19 @@ func parseFile(input io.Reader, pattern string) (Tabdata, error) {
 		} else {
 			// data processing
 			if len(pattern) > 0 {
-				if !patternR.MatchString(line) {
+				if patternR.MatchString(line) == InvertMatch {
+					// by default  -v is false, so if a  line does NOT
+					// match the pattern, we will ignore it. However,
+					// if the user specified -v, the matching is inverted,
+					// so we ignore all lines, which DO match.
 					continue
 				}
 			}
 
 			idx := 0 // we cannot use the header index, because we could exclude columns
-			for _, index := range data.headerIndices {
+			values := []string{}
-				value := ""
+			for _, part := range parts {
-
+				width := len(strings.TrimSpace(part))
-				if index["end"] == 0 {
-					value = string(line[index["beg"]:])
-				} else {
-					value = string(line[index["beg"]:index["end"]])
-				}
-
-				width := len(strings.TrimSpace(value))
 
 				if len(data.maxwidthPerCol)-1 < idx {
 					data.maxwidthPerCol = append(data.maxwidthPerCol, width)
@@ -142,7 +101,7 @@ func parseFile(input io.Reader, pattern string) (Tabdata, error) {
 				// if Debug {
 				// 	fmt.Printf("<%s> ", value)
 				// }
-				values = append(values, strings.TrimSpace(value))
+				values = append(values, strings.TrimSpace(part))
 
 				idx++
 			}
@@ -151,7 +110,7 @@ func parseFile(input io.Reader, pattern string) (Tabdata, error) {
 	}
 
 	if scanner.Err() != nil {
-		return data, errors.Unwrap(fmt.Errorf("Regexp pattern %s is invalid: %w", pattern, scanner.Err()))
+		return data, errors.Unwrap(fmt.Errorf("Failed to read from io.Reader: %w", scanner.Err()))
 	}
 
 	if Debug {

lib/parser_test.go

@@ -18,6 +18,7 @@ along with this program. If not, see <http://www.gnu.org/licenses/>.
 package lib
 
 import (
+	"fmt"
 	"reflect"
 	"strings"
 	"testing"
@@ -27,40 +28,18 @@ func TestParser(t *testing.T) {
 	data := Tabdata{
 		maxwidthHeader: 5,
 		maxwidthPerCol: []int{
-			5,
+			5, 5, 8,
-			5,
-			8,
 		},
 		columns: 3,
-		headerIndices: []map[string]int{
-			map[string]int{
-				"beg": 0,
-				"end": 6,
-			},
-			map[string]int{
-				"end": 13,
-				"beg": 7,
-			},
-			map[string]int{
-				"beg": 14,
-				"end": 0,
-			},
-		},
 		headers: []string{
-			"ONE",
+			"ONE", "TWO", "THREE",
-			"TWO",
-			"THREE",
 		},
 		entries: [][]string{
 			[]string{
-				"asd",
+				"asd", "igig", "cxxxncnc",
-				"igig",
-				"cxxxncnc",
 			},
 			[]string{
-				"19191",
+				"19191", "EDD 1", "X",
-				"EDD 1",
-				"X",
 			},
 		},
 	}
@@ -71,12 +50,63 @@ asd    igig   cxxxncnc
 
 	readFd := strings.NewReader(table)
 	gotdata, err := parseFile(readFd, "")
+	Separator = DefaultSeparator
 
 	if err != nil {
 		t.Errorf("Parser returned error: %s\nData processed so far: %+v", err, gotdata)
 	}
 
 	if !reflect.DeepEqual(data, gotdata) {
-		t.Errorf("Parser returned invalid data\nExp: %+v\nGot: %+v\n", data, gotdata)
+		t.Errorf("Parser returned invalid data, Regex: %s\nExp: %+v\nGot: %+v\n", Separator, data, gotdata)
+	}
+}
+
+func TestParserPatternmatching(t *testing.T) {
+	var tests = []struct {
+		entries [][]string
+		pattern string
+		invert  bool
+	}{
+		{
+			entries: [][]string{
+				[]string{
+					"asd", "igig", "cxxxncnc",
+				},
+			},
+			pattern: "ig",
+			invert:  false,
+		},
+		{
+			entries: [][]string{
+				[]string{
+					"19191", "EDD 1", "X",
+				},
+			},
+			pattern: "ig",
+			invert:  true,
+		},
+	}
+
+	table := `ONE    TWO    THREE  
+asd    igig   cxxxncnc  
+19191  EDD 1  X`
+
+	for _, tt := range tests {
+		testname := fmt.Sprintf("parse-with-inverted-pattern-%t", tt.invert)
+		t.Run(testname, func(t *testing.T) {
+			InvertMatch = tt.invert
+
+			readFd := strings.NewReader(table)
+			gotdata, err := parseFile(readFd, tt.pattern)
+
+			if err != nil {
+				t.Errorf("Parser returned error: %s\nData processed so far: %+v", err, gotdata)
+			}
+
+			if !reflect.DeepEqual(tt.entries, gotdata.entries) {
+				t.Errorf("Parser returned invalid data (pattern: %s, invert: %t)\nExp: %+v\nGot: %+v\n",
+					tt.pattern, tt.invert, tt.entries, gotdata.entries)
+			}
+		})
 	}
 }

lib/printer.go

@@ -19,49 +19,26 @@ package lib
 
 import (
 	"fmt"
+	"github.com/gookit/color"
 	"github.com/olekukonko/tablewriter"
-	"os"
 	"regexp"
 	"strings"
 )
 
 func printData(data *Tabdata) {
-	// prepare headers: add numbers to headers
+	// some output preparations:
-	numberedHeaders := []string{}
-	for i, head := range data.headers {
-		if len(Columns) > 0 {
-			// -c specified
-			if !contains(UseColumns, i+1) {
-				// ignore this one
-				continue
-			}
-		}
-		if NoNumbering {
-			numberedHeaders = append(numberedHeaders, head)
-		} else {
-			numberedHeaders = append(numberedHeaders, fmt.Sprintf("%s(%d)", head, i+1))
-		}
-	}
-	data.headers = numberedHeaders
 
-	// prepare data
+	if OutputMode != "shell" {
-	if len(Columns) > 0 {
+		// not needed in eval string
-		reducedEntries := [][]string{}
+		numberizeHeaders(data)
-		reducedEntry := []string{}
-		for _, entry := range data.entries {
-			reducedEntry = nil
-			for i, value := range entry {
-				if !contains(UseColumns, i+1) {
-					continue
-				}
-
-				reducedEntry = append(reducedEntry, value)
-			}
-			reducedEntries = append(reducedEntries, reducedEntry)
-		}
-		data.entries = reducedEntries
 	}
 
+	// remove unwanted columns, if any
+	reduceColumns(data)
+
+	// sort the data
+	sortTable(data, SortByColumn)
+
 	switch OutputMode {
 	case "extended":
 		printExtendedData(data)
@@ -107,14 +84,18 @@ func printOrgmodeData(data *Tabdata) {
 	leftR := regexp.MustCompile("(?m)^\\+")
 	rightR := regexp.MustCompile("\\+(?m)$")
 
-	fmt.Print(rightR.ReplaceAllString(leftR.ReplaceAllString(tableString.String(), "|"), "|"))
+	color.Print(
+		colorizeData(
+			rightR.ReplaceAllString(
+				leftR.ReplaceAllString(tableString.String(), "|"), "|")))
 }
 
 /*
    Markdown table
 */
 func printMarkdownData(data *Tabdata) {
-	table := tablewriter.NewWriter(os.Stdout)
+	tableString := &strings.Builder{}
+	table := tablewriter.NewWriter(tableString)
 
 	table.SetHeader(data.headers)
 
@@ -126,13 +107,15 @@ func printMarkdownData(data *Tabdata) {
 	table.SetCenterSeparator("|")
 
 	table.Render()
+	color.Print(colorizeData(tableString.String()))
 }
 
 /*
    Simple ASCII table without any borders etc, just like the input we expect
 */
 func printAsciiData(data *Tabdata) {
-	table := tablewriter.NewWriter(os.Stdout)
+	tableString := &strings.Builder{}
+	table := tablewriter.NewWriter(tableString)
 
 	table.SetHeader(data.headers)
 	table.AppendBulk(data.entries)
@@ -154,6 +137,7 @@ func printAsciiData(data *Tabdata) {
 	table.SetNoWhiteSpace(true)
 
 	table.Render()
+	color.Print(colorizeData(tableString.String()))
 }
 
 /*
@@ -161,22 +145,14 @@ func printAsciiData(data *Tabdata) {
 */
 func printExtendedData(data *Tabdata) {
 	// needed for data output
-	format := fmt.Sprintf("%%%ds: %%s\n", data.maxwidthHeader) // FIXME: re-calculate if -c has been set
+	format := fmt.Sprintf("%%%ds: %%s\n", data.maxwidthHeader)
 
 	if len(data.entries) > 0 {
-		var idx int
 		for _, entry := range data.entries {
-			idx = 0
 			for i, value := range entry {
-				if len(Columns) > 0 {
+				color.Printf(format, data.headers[i], value)
-					if !contains(UseColumns, i+1) {
-						continue
-					}
-				}
-
-				fmt.Printf(format, data.headers[idx], value)
-				idx++
 			}
+
 			fmt.Println()
 		}
 	}
@@ -190,6 +166,7 @@ func printShellData(data *Tabdata) {
 		var idx int
 		for _, entry := range data.entries {
 			idx = 0
+			shentries := []string{}
 			for i, value := range entry {
 				if len(Columns) > 0 {
 					if !contains(UseColumns, i+1) {
@@ -197,10 +174,10 @@ func printShellData(data *Tabdata) {
 					}
 				}
 
-				fmt.Printf("%s=\"%s\" ", data.headers[idx], value)
+				shentries = append(shentries, fmt.Sprintf("%s=\"%s\"", data.headers[idx], value))
 				idx++
 			}
-			fmt.Println()
+			fmt.Println(strings.Join(shentries, " "))
 		}
 	}
 }

lib/printer_test.go

@@ -18,64 +18,195 @@ along with this program. If not, see <http://www.gnu.org/licenses/>.
 package lib
 
 import (
+	"fmt"
+	"github.com/gookit/color"
 	"os"
 	"strings"
 	"testing"
 )
 
+func stdout2pipe(t *testing.T) (*os.File, *os.File) {
+	reader, writer, err := os.Pipe()
+	if err != nil {
+		t.Fatal(err)
+	}
+	origStdout := os.Stdout
+	os.Stdout = writer
+
+	// we need to tell the color mode the io.Writer, even if we don't usw colorization
+	color.SetOutput(writer)
+
+	return origStdout, reader
+}
+
 func TestPrinter(t *testing.T) {
-	table := `ONE    TWO    THREE  
+	startdata := Tabdata{
-asd    igig   cxxxncnc  
+		maxwidthHeader: 5,
-19191  EDD 1  X`
+		maxwidthPerCol: []int{
+			5,
+			5,
+			8,
+		},
+		columns: 3,
+		headers: []string{
+			"ONE", "TWO", "THREE",
+		},
+		entries: [][]string{
+			[]string{
+				"asd", "igig", "cxxxncnc",
+			},
+			[]string{
+				"19191", "EDD 1", "X",
+			},
+		},
+	}
 
 	expects := map[string]string{
 		"ascii": `ONE(1)	TWO(2)	THREE(3) 
 asd   	igig  	cxxxncnc	
 19191 	EDD 1 	X`,
+
 		"orgtbl": `|--------+--------+----------|
 | ONE(1) | TWO(2) | THREE(3) |
 |--------+--------+----------|
 | asd    | igig   | cxxxncnc |
 |  19191 | EDD 1  | X        |
 |--------+--------+----------|`,
+
 		"markdown": `| ONE(1) | TWO(2) | THREE(3) |
 |--------|--------|----------|
 | asd    | igig   | cxxxncnc |
 |  19191 | EDD 1  | X        |`,
+
+		"shell": `ONE="asd" TWO="igig" THREE="cxxxncnc"
+ONE="19191" TWO="EDD 1" THREE="X"`,
+
+		"extended": `ONE(1): asd
+  TWO(2): igig
+THREE(3): cxxxncnc
+
+  ONE(1): 19191
+  TWO(2): EDD 1
+THREE(3): X`,
 	}
 
-	r, w, err := os.Pipe()
+	NoColor = true
-	if err != nil {
+	SortByColumn = 0 // disable sorting
-		t.Fatal(err)
+
-	}
+	origStdout, reader := stdout2pipe(t)
-	origStdout := os.Stdout
-	os.Stdout = w
 
 	for mode, expect := range expects {
-		OutputMode = mode
+		testname := fmt.Sprintf("print-%s", mode)
-		fd := strings.NewReader(table)
+		t.Run(testname, func(t *testing.T) {
-		data, err := parseFile(fd, "")
 
-		if err != nil {
+			OutputMode = mode
-			t.Errorf("Parser returned error: %s\nData processed so far: %+v", err, data)
+			data := startdata // we need to reset our mock data, since it's being modified in printData()
-		}
+			printData(&data)
 
-		printData(&data)
+			buf := make([]byte, 1024)
+			n, err := reader.Read(buf)
+			if err != nil {
+				t.Fatal(err)
+			}
+			buf = buf[:n]
+			output := strings.TrimSpace(string(buf))
 
-		buf := make([]byte, 1024)
+			if output != expect {
-		n, err := r.Read(buf)
+				t.Errorf("output mode: %s, got:\n%s\nwant:\n%s\n (%d <=> %d)",
-		if err != nil {
+					mode, output, expect, len(output), len(expect))
-			t.Fatal(err)
+			}
-		}
+		})
-		buf = buf[:n]
-		output := strings.TrimSpace(string(buf))
-
-		if output != expect {
-			t.Errorf("output mode: %s, got:\n%s\nwant:\n%s\n (%d <=> %d)", mode, output, expect, len(output), len(expect))
-		}
 	}
 
 	// Restore
 	os.Stdout = origStdout
 
 }
+
+func TestSortPrinter(t *testing.T) {
+	startdata := Tabdata{
+		maxwidthHeader: 5,
+		maxwidthPerCol: []int{
+			3,
+			3,
+			2,
+		},
+		columns: 3,
+		headers: []string{
+			"ONE", "TWO", "THREE",
+		},
+		entries: [][]string{
+			[]string{
+				"abc", "345", "b1",
+			},
+			[]string{
+				"bcd", "234", "a2",
+			},
+			[]string{
+				"cde", "123", "c3",
+			},
+		},
+	}
+
+	var tests = []struct {
+		data   Tabdata
+		sortby int
+		expect string
+	}{
+		{
+			data:   startdata,
+			sortby: 1,
+			expect: `ONE(1)	TWO(2)	THREE(3) 
+abc   	345   	b1      	
+bcd   	234   	a2      	
+cde   	123   	c3`,
+		},
+
+		{
+			data:   startdata,
+			sortby: 2,
+			expect: `ONE(1)	TWO(2)	THREE(3) 
+cde   	123   	c3      	
+bcd   	234   	a2      	
+abc   	345   	b1`,
+		},
+
+		{
+			data:   startdata,
+			sortby: 3,
+			expect: `ONE(1)	TWO(2)	THREE(3) 
+bcd   	234   	a2      	
+abc   	345   	b1      	
+cde   	123   	c3`,
+		},
+	}
+
+	NoColor = true
+	OutputMode = "ascii"
+	origStdout, reader := stdout2pipe(t)
+
+	for _, tt := range tests {
+		testname := fmt.Sprintf("print-sorted-table-%d", tt.sortby)
+		t.Run(testname, func(t *testing.T) {
+			SortByColumn = tt.sortby
+
+			printData(&tt.data)
+
+			buf := make([]byte, 1024)
+			n, err := reader.Read(buf)
+			if err != nil {
+				t.Fatal(err)
+			}
+			buf = buf[:n]
+			output := strings.TrimSpace(string(buf))
+
+			if output != tt.expect {
+				t.Errorf("sort column: %d, got:\n%s\nwant:\n%s",
+					tt.sortby, output, tt.expect)
+			}
+		})
+	}
+
+	// Restore
+	os.Stdout = origStdout
+}

lib/sort.go

@@ -0,0 +1,46 @@
+/*
+Copyright © 2022 Thomas von Dein
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package lib
+
+import (
+	"sort"
+)
+
+func sortTable(data *Tabdata, col int) {
+	if col <= 0 {
+		// no sorting wanted
+		return
+	}
+
+	col-- // ui starts counting by 1, but use 0 internally
+
+	// sanity checks
+	if len(data.entries) == 0 {
+		return
+	}
+
+	if col >= len(data.headers) {
+		// fall back to default column
+		col = 0
+	}
+
+	// actual sorting
+	sort.SliceStable(data.entries, func(i, j int) bool {
+		return data.entries[i][col] < data.entries[j][col]
+	})
+}

mkrel.sh

@@ -43,7 +43,7 @@ for D in $DIST; do
     tardir="${tool}-${os}-${arch}-${version}"
     tarfile="releases/${tool}-${os}-${arch}-${version}.tar.gz"
     set -x
-    GOOS=${os} GOARCH=${arch} go build -o ${binfile}
+    GOOS=${os} GOARCH=${arch} go build -o ${binfile} -ldflags "-X 'github.com/tlinden/tablizer/lib.VERSION=${version}'"
     mkdir -p ${tardir}
     cp ${binfile} README.md LICENSE ${tardir}/
     echo 'tool = tablizer

tablizer.1

@@ -133,7 +133,7 @@
 .\" ========================================================================
 .\"
 .IX Title "TABLIZER 1"
-.TH TABLIZER 1 "2022-10-04" "1" "User Commands"
+.TH TABLIZER 1 "2022-10-13" "1" "User Commands"
 .\" For nroff, turn off justification.  Always turn off hyphenation; it makes
 .\" way too many mistakes in technical documents.
 .if n .ad l
@@ -150,22 +150,26 @@ tablizer \- Manipulate tabular output of other programs
 \&      \-c, \-\-columns string     Only show the speficied columns (separated by ,)
 \&      \-d, \-\-debug              Enable debugging
 \&      \-h, \-\-help               help for tablizer
+\&      \-v, \-\-invert\-match       select non\-matching rows
+\&      \-m, \-\-man                Display manual page
 \&      \-n, \-\-no\-numbering       Disable header numbering
+\&      \-N, \-\-no\-color           Disable pattern highlighting
 \&      \-o, \-\-output string      Output mode \- one of: orgtbl, markdown, extended, ascii(default)
 \&      \-X, \-\-extended           Enable extended output
 \&      \-M, \-\-markdown           Enable markdown table output
 \&      \-O, \-\-orgtbl             Enable org\-mode table output
 \&      \-s, \-\-separator string   Custom field separator
+\&      \-k, \-\-sort\-by int        Sort by column (default: 1)
 \&      \-v, \-\-version            Print program version
 .Ve
 .SH "DESCRIPTION"
 .IX Header "DESCRIPTION"
-Many  programs generate  tabular  output.  But  sometimes  you need  to
+Many  programs generate  tabular output.   But sometimes  you need  to
 post-process these tables, you may need  to remove one or more columns
-or you may want to filter for  some pattern or you may need the output
+or you  may want to filter  for some pattern (See  \s-1PATTERNS\s0) or you
-in another program and need to  parse it somehow.  Standard unix tools
+may need the  output in another program and need  to parse it somehow.
-such as  \fBawk\fR\|(1), \fBgrep\fR\|(1) or \fBcolumn\fR\|(1)  may help, but sometimes  it's a
+Standard unix tools such as \fBawk\fR\|(1), \fBgrep\fR\|(1) or \fBcolumn\fR\|(1) may help, but
-tedious business.
+sometimes it's a tedious business.
 .PP
 Let's take  the output of  the tool  kubectl.  It contains  cells with
 withespace and they do not separate columns by \s-1TAB\s0 characters. This is
@@ -179,8 +183,9 @@ positions.
 .PP
 Without any options it reads its input from \f(CW\*(C`STDIN\*(C'\fR, but you can also
 specify a  file as a  parameter. If you want  to reduce the  output by
-some   regular   expression,   just    specify   it   as   its   first
+some regular expression,  just specify it as its  first parameter. You
-parameters. Hence:
+may also  use the  \fB\-v\fR option  to exclude all  rows which  match the
+pattern. Hence:
 .PP
 .Vb 2
 \&   # read from STDIN
@@ -215,8 +220,47 @@ the original order.
 .PP
 The numbering can be suppressed by using the \fB\-n\fR option.
 .PP
+By  default, if  a  \fBpattern\fR  has been  speficied,  matches will  be
+highlighted. You can disable this behavior with the \fB\-N\fR option.
+.PP
+Use the  \fB\-k\fR option to specify  by which column to  sort the tabular
+data (as in \s-1GNU\s0 \fBsort\fR\|(1)). The default sort column is the first one. To
+disable sorting at all, supply 0 (Zero) to \-k.
+.PP
 Finally the  \fB\-d\fR option  enables debugging  output which  is mostly
 usefull for the developer.
+.SS "\s-1PATTERNS\s0"
+.IX Subsection "PATTERNS"
+You can reduce the rows being  displayed by using a regular expression
+pattern.  The  regexp is  \s-1PCRE\s0 compatible, refer  to the  syntax cheat
+sheet here: <https://github.com/google/re2/wiki/Syntax>.  If you want
+to read  a more comprehensive  documentation about the topic  and have
+perl installed you can read it with:
+.PP
+.Vb 1
+\&    perldoc perlre
+.Ve
+.PP
+Or read it online: <https://perldoc.perl.org/perlre>.
+.PP
+A note on  modifiers: the regexp engine used in  tablizer uses another
+modifier syntax:
+.PP
+.Vb 1
+\&    (?MODIFIER)
+.Ve
+.PP
+The most important modifiers are:
+.PP
+\&\f(CW\*(C`i\*(C'\fR ignore case
+\&\f(CW\*(C`m\*(C'\fR multiline mode
+\&\f(CW\*(C`s\*(C'\fR single line mode
+.PP
+Example for a case insensitve search:
+.PP
+.Vb 1
+\&    kubectl get pods \-A | tablizer "(?i)account"
+.Ve
 .SS "\s-1OUTPUT MODES\s0"
 .IX Subsection "OUTPUT MODES"
 There might be cases  when the tabular output of a  program is way too

tablizer.pod

@@ -11,23 +11,27 @@ tablizer - Manipulate tabular output of other programs
       -c, --columns string     Only show the speficied columns (separated by ,)
       -d, --debug              Enable debugging
       -h, --help               help for tablizer
+      -v, --invert-match       select non-matching rows
+      -m, --man                Display manual page
       -n, --no-numbering       Disable header numbering
+      -N, --no-color           Disable pattern highlighting
       -o, --output string      Output mode - one of: orgtbl, markdown, extended, ascii(default)
       -X, --extended           Enable extended output
       -M, --markdown           Enable markdown table output
       -O, --orgtbl             Enable org-mode table output
       -s, --separator string   Custom field separator
+      -k, --sort-by int        Sort by column (default: 1)
       -v, --version            Print program version
 
 
 =head1 DESCRIPTION
 
-Many  programs generate  tabular  output.  But  sometimes  you need  to
+Many  programs generate  tabular output.   But sometimes  you need  to
 post-process these tables, you may need  to remove one or more columns
-or you may want to filter for  some pattern or you may need the output
+or you  may want to filter  for some pattern (See  L<PATTERNS>) or you
-in another program and need to  parse it somehow.  Standard unix tools
+may need the  output in another program and need  to parse it somehow.
-such as  awk(1), grep(1) or column(1)  may help, but sometimes  it's a
+Standard unix tools such as awk(1), grep(1) or column(1) may help, but
-tedious business.
+sometimes it's a tedious business.
 
 Let's take  the output of  the tool  kubectl.  It contains  cells with
 withespace and they do not separate columns by TAB characters. This is
@@ -41,8 +45,9 @@ positions.
 
 Without any options it reads its input from C<STDIN>, but you can also
 specify a  file as a  parameter. If you want  to reduce the  output by
-some   regular   expression,   just    specify   it   as   its   first
+some regular expression,  just specify it as its  first parameter. You
-parameters. Hence:
+may also  use the  B<-v> option  to exclude all  rows which  match the
+pattern. Hence:
 
    # read from STDIN
    kubectl get pods | tablizer
@@ -71,9 +76,44 @@ the original order.
 
 The numbering can be suppressed by using the B<-n> option.
 
+By  default, if  a  B<pattern>  has been  speficied,  matches will  be
+highlighted. You can disable this behavior with the B<-N> option.
+
+Use the  B<-k> option to specify  by which column to  sort the tabular
+data (as in GNU sort(1)). The default sort column is the first one. To
+disable sorting at all, supply 0 (Zero) to -k.
+
 Finally the  B<-d> option  enables debugging  output which  is mostly
 usefull for the developer.
 
+=head2 PATTERNS
+
+You can reduce the rows being  displayed by using a regular expression
+pattern.  The  regexp is  PCRE compatible, refer  to the  syntax cheat
+sheet here: L<https://github.com/google/re2/wiki/Syntax>.  If you want
+to read  a more comprehensive  documentation about the topic  and have
+perl installed you can read it with:
+
+    perldoc perlre
+
+Or read it online: L<https://perldoc.perl.org/perlre>.
+
+A note on  modifiers: the regexp engine used in  tablizer uses another
+modifier syntax:
+
+    (?MODIFIER)
+
+The most important modifiers are:
+
+C<i> ignore case
+C<m> multiline mode
+C<s> single line mode
+
+Example for a case insensitve search:
+
+    kubectl get pods -A | tablizer "(?i)account"
+
+
 =head2 OUTPUT MODES
 
 There might be cases  when the tabular output of a  program is way too