From 35310ec6740b555ba1ab1260e50ed905cc4b5ac2 Mon Sep 17 00:00:00 2001
From: trimstray <trimstray@gmail.com>
Date: Tue, 26 Nov 2019 08:41:03 +0100
Subject: [PATCH] add new awk one-liners - signed-off-by: trimstray
 <trimstray@gmail.com>

---
 README.md | 117 +++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 106 insertions(+), 11 deletions(-)

diff --git a/README.md b/README.md
index 24e1757..b0dbcd7 100644
--- a/README.md
+++ b/README.md
@@ -3685,10 +3685,25 @@ python -m base64 -d <<< "dGhpcyBpcyBlbmNvZGVkCg=="
 
 ##### Tool: [awk](http://www.grymoire.com/Unix/Awk.html)
 
-###### Remove duplicate entries in a file without sorting
+###### Search for matching lines
 
 ```bash
-awk '!x[$0]++' filename
+# egrep foo
+awk '/foo/' filename
+```
+
+###### Search non matching lines
+
+```bash
+# egrep -v foo
+awk '!/foo/' filename
+```
+
+###### Print matching lines with numbers
+
+```bash
+# egrep -n foo
+awk '/foo/{print FNR,$0}' filename
 ```
 
 ###### Print the last column
@@ -3697,6 +3712,55 @@ awk '!x[$0]++' filename
 awk '{print $NF}' filename
 ```
 
+###### Find all the lines longer than 80 characters
+
+```bash
+awk 'length($0)>80{print FNR,$0}' filename
+```
+
+###### Print only lines of less than 80 characters
+
+```bash
+awk 'length < 80 filename
+```
+
+###### Print double new lines a file
+
+```bash
+awk '1; { print "" }' filename
+```
+
+###### Print line numbers
+
+```bash
+awk '{ print FNR "\t" $0 }' filename
+awk '{ printf("%5d : %s\n", NR, $0) }' filename   # in a fancy manner
+```
+
+###### Print line numbers for only non-blank lines
+
+```bash
+awk 'NF { $0=++a " :" $0 }; { print }' filename
+```
+
+###### Print the line and the next two (i=5) lines after the line matching regexp
+
+```bash
+awk '/foo/{i=5+1;}{if(i){i--; print;}}' filename
+```
+
+###### Print the lines starting at the line matching 'server {' until the line matching '}'
+
+```bash
+awk '/server {/,/}/' filename
+```
+
+###### Print multiple columns with separators
+
+```bash
+awk -F' ' '{print "ip:\t" $2 "\n port:\t" $3' filename
+```
+
 ###### Remove empty lines
 
 ```bash
@@ -3706,10 +3770,29 @@ awk 'NF > 0' filename
 awk NF filename
 ```
 
-###### Print multiple columns with separators
+###### Delete trailing white space (spaces, tabs)
 
 ```bash
-awk -F' ' '{print "ip:\t" $2 "\n port:\t" $3' filename
+awk '{sub(/[ \t]*$/, "");print}' filename
+```
+
+###### Delete leading white space
+
+```bash
+awk '{sub(/^[ \t]+/, ""); print}' filename
+```
+
+###### Remove duplicate consecutive lines
+
+```bash
+# uniq
+awk 'a !~ $0{print}; {a=$0}' filename
+```
+
+###### Remove duplicate entries in a file without sorting
+
+```bash
+awk '!x[$0]++' filename
 ```
 
 ###### Exclude multiple columns
@@ -3718,6 +3801,18 @@ awk -F' ' '{print "ip:\t" $2 "\n port:\t" $3' filename
 awk '{$1=$3=""}1' filename
 ```
 
+###### Substitute foo for bar on lines matching regexp
+
+```bash
+awk '/regexp/{gsub(/foo/, "bar")};{print}' filename
+```
+
+###### Add some characters at the beginning of matching lines
+
+```bash
+awk '/regexp/{sub(/^/, "++++"); print;next;}{print}' filename
+```
+
 ###### Get the last hour of Apache logs
 
 ```bash
@@ -3729,7 +3824,7 @@ ___
 
 ##### Tool: [sed](http://www.grymoire.com/Unix/Sed.html)
 
-###### To print a specific line from a file
+###### Print a specific line from a file
 
 ```bash
 sed -n 10p /path/to/file
@@ -3790,12 +3885,6 @@ grep -RnisI "pattern" *
 fgrep "pattern" * -R
 ```
 
-###### Remove blank lines from a file and save output to new file
-
-```bash
-grep . filename > newfilename
-```
-
 ###### Show only for multiple patterns
 
 ```bash
@@ -3832,6 +3921,12 @@ grep -- -- filename
 grep "\-\-" filename
 ```
 
+###### Remove blank lines from a file and save output to new file
+
+```bash
+grep . filename > newfilename
+```
+
 ##### Tool: [perl](https://www.perl.org/)
 
 ###### Search and replace (in place)