add template output mode

cmd/tablizer.go

@@ -34,6 +34,7 @@ SYNOPSIS
           -J, --jsonout                      Enable JSON output
           -C, --csv                          Enable CSV output
           -A, --ascii                        Default output mode, ascii tabular
+          -P, --template <tpl>               Enable template mode with template <tpl>
           -L, --hightlight-lines             Use alternating background colors for tables
           -o, --ofs <char>                   Output field separator, used by -A and -C. 
           -y, --yank-columns                 Yank specified columns (separated by ,) to clipboard,
@@ -77,16 +78,16 @@ DESCRIPTION
     use the -v option to exclude all rows which match the pattern. Hence:
 
        # read from STDIN
-       kubectl get pods | tablizer
+       > kubectl get pods | tablizer
 
        # read a file
-       tablizer -r filename
+       > tablizer -r filename
 
        # search for pattern in a file (works like grep)
-       tablizer regex -r filename
+       > tablizer regex -r filename
 
        # search for pattern in STDIN
-       kubectl get pods | tablizer regex
+       > kubectl get pods | tablizer regex
 
     The output looks like the original one. You can add the option -n, then
     every header field will have a numer associated with it, e.g.:
@@ -96,18 +97,18 @@ DESCRIPTION
     These numbers denote the column and you can use them to specify which
     columns you want to have in your output (see COLUMNS:
 
-       kubectl get pods | tablizer -c1,3
+       > kubectl get pods | tablizer -c1,3
 
     You can specify the numbers in any order but output will always follow
     the original order.
 
     However, you may also just use the header names instead of numbers, eg:
 
-       kubectl get pods | tablizer -cname,status
+       > kubectl get pods | tablizer -cname,status
 
     You can also use regular expressions with -c, eg:
 
-       kubectl get pods | tablizer -c '[ae]'
+       > kubectl get pods | tablizer -c '[ae]'
 
     By default tablizer shows a header containing the names of each column.
     This can be disabled using the -H option. Be aware that this only
@@ -218,7 +219,7 @@ DESCRIPTION
 
     Example for a case insensitive search:
 
-        kubectl get pods -A | tablizer "/account/i"
+        > kubectl get pods -A | tablizer "/account/i"
 
     If you use the "!" flag, then the regex match will be negated, that is,
     if a line in the input matches the given regex, but "!" is supplied,
@@ -284,7 +285,7 @@ DESCRIPTION
 
     We want to see only the CMD column and use a regex for this:
 
-        ps | tablizer -s '\s+' -c C
+        > ps | tablizer -s '\s+' -c C
         CMD(4)
         bash
         ps
@@ -315,7 +316,7 @@ DESCRIPTION
 
     Example:
 
-        cat t/testtable2
+        > cat t/testtable2
         NAME  DURATION
         x     10
         a     100
@@ -323,7 +324,7 @@ DESCRIPTION
         u     4
         k     6
     
-        cat t/testtable2 | tablizer -T2 -R '/^\d/4/' -n
+        > cat t/testtable2 | tablizer -T2 -R '/^\d/4/' -n
         NAME    DURATION 
         x       40      
         a       400     
@@ -339,7 +340,7 @@ DESCRIPTION
     header left, value right, aligned by the field widths. Here's an
     example:
 
-        kubectl get pods | ./tablizer -o extended
+        > kubectl get pods | ./tablizer -o extended
             NAME: repldepl-7bcd8d5b64-7zq4l  
            READY: 1/1    
           STATUS: Running  
@@ -352,7 +353,7 @@ DESCRIPTION
     The option -o shell can be used if the output has to be processed by the
     shell, it prints variable assignments for each cell, one line per row:
 
-        kubectl get pods | ./tablizer -o extended ./tablizer -o shell
+        > kubectl get pods | ./tablizer -o extended ./tablizer -o shell
         NAME="repldepl-7bcd8d5b64-7zq4l" READY="1/1" STATUS="Running" RESTARTS="9 (47m ago)" AGE="4d23h" 
         NAME="repldepl-7bcd8d5b64-m48n8" READY="1/1" STATUS="Running" RESTARTS="9 (47m ago)" AGE="4d23h" 
         NAME="repldepl-7bcd8d5b64-q2bf4" READY="1/1" STATUS="Running" RESTARTS="9 (47m ago)" AGE="4d23h"
@@ -364,6 +365,18 @@ DESCRIPTION
     markdown which prints a Markdown table, yaml, which prints yaml encoding
     and CSV mode, which prints a comma separated value file.
 
+    A special output mode ist the Template mode, activated with the option
+    "--template". Template language is the Golang template language:
+    <https://pkg.go.dev/text/template>. You can also use lot's of additional
+    functions from: <https://masterminds.github.io/sprig/>. Here's an
+    example:
+
+        > kubectl get pods | tablizer --template "{{.name}} is {{.status}}"
+        alertmanager-kube-prometheus-alertmanager-0 is Running
+        grafana-fcc54cbc9-bk7s8 is Running
+
+    You can use header names as variables.
+
   PUT FIELDS TO CLIPBOARD
     You can let tablizer put fields to the clipboard using the option "-y".
     This best fits the use-case when the result of your filtering yields
@@ -532,6 +545,7 @@ Output Flags (mutually exclusive):
   -J, --jsonout                      Enable JSON output
   -C, --csv                          Enable CSV output
   -A, --ascii                        Default output mode, ascii tabular
+  -P, --template <tpl>               Enable template mode with template <tpl>
   -L, --hightlight-lines             Use alternating background colors for tables
   -o, --ofs <char>                   Output field separator, used by -A and -C. 
   -y, --yank-columns                 Yank specified columns (separated by ,) to clipboard,