updates for version 1.3

learnbyexample · May 20, 2020 · 2a69a4d · 2a69a4d
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diff --git a/code_snippets/Adding_content_from_file.sh b/code_snippets/Adding_content_from_file.sh
@@ -1,3 +1,5 @@
+## r for entire file
+
 cat ip.txt
 
 cat fav_colors.txt
@@ -18,12 +20,16 @@ printf '%b' "$items" | sed -e '2 {r /dev/stdin' -e 'd}' ip.txt
 
 sed -e '/^red/r ip.txt' -e '/yellow/,//d' fav_colors.txt
 
+## Using e and cat command
+
 sed '/red/e cat ip.txt' fav_colors.txt
 
 text='good\tone\nfood\tpun'
 
 echo "$text" | sed '1e cat /dev/stdin' ip.txt
 
+## R for line by line
+
 sed '/red/R ip.txt' fav_colors.txt
 
 seq 4 | sed 'R /dev/stdin' fav_colors.txt

diff --git a/code_snippets/BRE_ERE_Regular_Expressions.sh b/code_snippets/BRE_ERE_Regular_Expressions.sh
@@ -1,3 +1,5 @@
+## Line Anchors
+
 printf 'spared no one\npar\nspar\n' | sed -n '/^sp/p'
 
 printf 'spared no one\npar\nspar\n' | sed -n '/ar$/p'
@@ -8,6 +10,8 @@ printf 'spared no one\npar\nspar\n' | sed 's/^/* /'
 
 printf 'spared no one\npar\nspar\n' | sed '/ /! s/$/./'
 
+## Word Anchors
+
 cat word_anchors.txt
 
 sed -n '/\bpar/p' word_anchors.txt
@@ -26,6 +30,8 @@ echo 'copper' | sed 's/\b/:/g'
 
 echo 'copper' | sed 's/\B/:/g'
 
+## Alternation
+
 sed -n '/two\|sub/p' word_anchors.txt
 
 sed -nE '/two|sub/p' word_anchors.txt
@@ -42,6 +48,10 @@ echo 'spared party parent' | sed -E 's/spa|spared/**/g'
 
 echo 'spared party parent' | sed -E 's/spared|spa/**/g'
 
+echo 'spared party parent' | perl -pe 's/spa|spared/**/'
+
+## Grouping
+
 printf 'red\nreform\nread\narrest\n' | sed -nE '/reform|rest/p'
 
 printf 'red\nreform\nread\narrest\n' | sed -nE '/re(form|st)/p'
@@ -52,6 +62,8 @@ printf 'sub par\nspare\npart time\n' | sed -nE '/\b(par|part)\b/p'
 
 printf 'sub par\nspare\npart time\n' | sed -nE '/\bpar(|t)\b/p'
 
+## Matching the metacharacters
+
 echo 'a^2 + b^2 - C*3' | sed -n '/b^2/p'
 
 echo '$a = $b + $c' | sed -n '/$b/p'
@@ -62,6 +74,8 @@ printf '(a/b) + c\n3 + (a/b) - c\n' | sed -n '/^(a\/b)/p'
 
 printf '(a/b) + c\n3 + (a/b) - c\n' | sed -nE '/^\(a\/b\)/p'
 
+## Using different delimiters
+
 echo '/home/learnbyexample/reports' | sed 's/\/home\/learnbyexample\//~\//'
 
 echo '/home/learnbyexample/reports' | sed 's#/home/learnbyexample/#~/#'
@@ -74,12 +88,16 @@ printf '/foo/bar/1\n/foo/baz/1\n'
 
 printf '/foo/bar/1\n/foo/baz/1\n' | sed -n '\;/foo/bar/;p'
 
+## The dot meta character
+
 echo 'tac tin cot abc:tyz excited' | sed 's/c.t/-/g'
 
 printf '42\t35\n' | sed 's/.3.//'
 
 printf 'abc\nxyz\n' | sed 'N; s/c.x/ /'
 
+## Quantifiers
+
 echo 'fed fold fe:d feeder' | sed -E 's/\bfe.?d\b/X/g'
 
 printf 'sub par\nspare\npart time\n' | sed -nE '/\bpart?\b/p'
@@ -114,6 +132,8 @@ echo 'two cats and a dog' | sed -E 's/cat.*dog|dog.*cat/pets/'
 
 echo 'two dogs and a cat' | sed -E 's/cat.*dog|dog.*cat/pets/'
 
+## Longest match wins
+
 echo 'foot' | sed -E 's/f.?o/X/'
 
 echo 'car bat cod map scat dot abacus' | sed 's/.*/X/'
@@ -130,6 +150,8 @@ echo 'car bat cod map scat dot abacus' | sed 's/b.*at/-/'
 
 echo 'car bat cod map scat dot abacus' | sed 's/a.*m*/-/'
 
+## Character classes
+
 printf 'cute\ncat\ncot\ncoat\ncost\nscuttle\n' | sed -n '/c[ou]t/p'
 
 printf 'meeting\ncute\nboat\nat\nfoot\n' | sed -nE '/.[aeo]+t/p'
@@ -182,6 +204,8 @@ echo 'int a[5]' | sed -n '/[x[y.]/p'
 
 echo 'f*(a^b) - 3*(a+b)/(a-b)' | sed 's/a[+^]b/c/g'
 
+## Escape sequences
+
 printf 'foo\tbar\tbaz\n' | sed 's/\t/ /g'
 
 echo 'a b c' | sed 's/ /\t/g'
@@ -198,6 +222,8 @@ echo 'hello world' | sed 's/.*/"&"/'
 
 echo 'hello world' | sed 's/.*/"\x26"/'
 
+## Backreferences
+
 echo 'effort flee facade oddball rat tool' | sed -E 's/\w*(\w)\1\w*/X/g'
 
 echo '\[\] and \\w and \[a-zA-Z0-9\_\]' | sed -E 's/(\\?)\\/\1/g'
@@ -214,13 +240,35 @@ echo 'hello world' | sed 's/.*/Hi. &. Have a nice day/'
 
 echo 'one,2,3.14,42' | sed -E 's/^(([^,]+,){2})([^,]+)/\1"\3"/'
 
-sed -nE '/^(\w*(\w)\2\w*){2}$/p' words.txt | head -n5
+s='tryst,fun,glyph,pity,why,group'
 
-sed -nE '/^\w*(\w)\1\w*(\w)\2\w*$/p' words.txt | head -n5
+echo "$s" | sed -E 's/\b\w+\b|(\b[gp]\w*y\w*\b)/\1/g'
+
+echo "$s" | sed -E 's/(\b[gp]\w*y\w*\b)|\b\w+\b/\1/g'
 
 echo 'foo and bar' | sed 's/and/[&]/'
 
 echo 'foo and bar' | sed 's/and/[\&]/'
 
 echo 'foo and bar' | sed 's/and/\\/'
 
+## Known Bugs
+
+sed -nE '/^(\w*(\w)\2\w*){2}$/p' words.txt | head -n5
+
+sed -nE '/^\w*(\w)\1\w*(\w)\2\w*$/p' words.txt | head -n5
+
+echo 'cocoa' | sed -nE '/(\bco){2}/p'
+
+echo 'cocoa' | sed -nE '/\bco\bco/p'
+
+echo 'it line with it here sit too' | sed -E 's/with(.*\bit\b){2}/XYZ/'
+
+echo 'it line with it here sit too' | sed -E 's/with.*\bit\b.*\bit\b/XYZ/'
+
+echo 'it line with it here sit too' | sed -E 's/with(.*\<it\>){2}/XYZ/'
+
+echo 'it line with it here it too' | sed -E 's/with(.*\<it\>){2}/XYZ/'
+
+echo 'it line with it here it too sit' | sed -E 's/with(.*\<it\>){2}/XYZ/'
+
diff --git a/code_snippets/Control_structures.sh b/code_snippets/Control_structures.sh
@@ -1,3 +1,5 @@
+## if-then-else
+
 cat nums.txt
 
 sed '/^-/{s///; b}; s/^/-/' nums.txt
@@ -8,6 +10,8 @@ printf 'good\nbad\n' | sed 's/o/-/g; T; s/d/*/g'
 
 printf 'good\nbad\nneed\n' | sed 's/o/-/g; s/a/%/g; T; a ----'
 
+## loop
+
 echo '12345 hello42' | sed -E ':a s/^(\**)[0-9]/\1*/; ta'
 
 echo '123x45 hello42' | sed -E ':a s/^(\**)[0-9]/\1*/; ta'

diff --git a/code_snippets/Flags.sh b/code_snippets/Flags.sh
@@ -1,9 +1,13 @@
+## Case insensitive matching
+
 printf 'Cat\ncOnCaT\nscatter\ncot\n' | sed -n '/cat/p'
 
 printf 'Cat\ncOnCaT\nscatter\ncot\n' | sed -n '/cat/Ip'
 
 printf 'Cat\ncOnCaT\nscatter\ncot\n' | sed 's/cat/dog/I'
 
+## Changing case in replacement section
+
 echo 'hello there. how are you?' | sed 's/\b\w/\u&/g'
 
 echo 'HELLO THERE. HOW ARE YOU?' | sed 's/\b\w/\l&/g'
@@ -22,10 +26,14 @@ echo 'HeLLo:bYe gOoD:beTTEr' | sed -E 's/[a-z]+/\L\u&/Ig'
 
 echo 'HeLLo:bYe gOoD:beTTEr' | sed -E 's/[a-z]+/\U\l&/Ig'
 
+## Global replace
+
 printf '1,2,3,4\na,b,c,d\n' | sed 's/,/-/'
 
 printf '1,2,3,4\na,b,c,d\n' | sed 's/,/-/g'
 
+## Replace specific occurrences
+
 echo 'foo:123:bar:baz' | sed 's/:/-/'
 
 echo 'foo:123:bar:baz' | sed -E 's/[^:]+/"&"/'
@@ -54,10 +62,14 @@ echo '456:foo:123:bar:789:baz' | sed 's/:/[]/3; s/:/[]/2'
 
 echo '456:foo:123:bar:789:baz' | sed 's/:/[]/5; s/:/[]/3; s/:/[]/2'
 
+## Print flag
+
 echo 'hi there. have a nice day' | sed -n 's/xyz/XYZ/p'
 
 echo 'hi there. have a nice day' | sed -n 's/\bh/H/pg'
 
+## Write to a file
+
 seq 20 | sed -n 's/3/three/w 3.txt'
 
 cat 3.txt
@@ -76,6 +88,8 @@ sed -i 's/three/3/w /dev/stdout' 3.txt
 
 cat 3.txt
 
+## Executing external commands
+
 printf 'Date:\nreplace this line\n'
 
 printf 'Date:\nreplace this line\n' | sed 's/^replace.*/date/e'
@@ -92,6 +106,8 @@ printf 'date\ndate -I\n' | sed '2e'
 
 printf 'show\nexample\n' | sed '/am/e seq 2'
 
+## Multiline mode
+
 printf 'Hi there\nHave a Nice Day\n' | sed 'N; s/H.*e/X/'
 
 printf 'Hi there\nHave a Nice Day\n' | sed 'N; s/H.*e/X/gm'

diff --git a/code_snippets/Inplace_file_editing.sh b/code_snippets/Inplace_file_editing.sh
@@ -1,3 +1,5 @@
+## With backup
+
 cat colors.txt
 
 sed -i.bkp 's/blue/green/' colors.txt
@@ -6,12 +8,16 @@ cat colors.txt
 
 cat colors.txt.bkp
 
+## Without backup
+
 cat fruits.txt
 
 sed -i 's/an/AN/g' fruits.txt
 
 cat fruits.txt
 
+## Multiple files
+
 cat f1.txt
 
 cat f2.txt
@@ -24,12 +30,16 @@ cat f1.txt
 
 cat f2.txt
 
+## Prefix backup name
+
 ls *colors*
 
 sed -i'bkp.*' 's/green/yellow/' colors.txt
 
 ls *colors*
 
+## Place backups in different directory
+
 mkdir backups
 
 sed -i'backups/*' 's/good/nice/' f1.txt f2.txt

diff --git a/code_snippets/Introduction.sh b/code_snippets/Introduction.sh
@@ -1,8 +1,10 @@
-wget https://ftp.gnu.org/gnu/sed/sed-4.7.tar.xz
+## Installation
 
-tar -Jxf sed-4.7.tar.xz
+wget https://ftp.gnu.org/gnu/sed/sed-4.8.tar.xz
 
-cd sed-4.7/
+tar -Jxf sed-4.8.tar.xz
+
+cd sed-4.8/
 
 ./configure 
 
@@ -14,16 +16,22 @@ type -a sed
 
 sed --version | head -n1
 
+## Documentation and options overview
+
 man sed
 
 sed --help
 
+## Editing standard input
+
 printf '1,2,3,4\na,b,c,d\n'
 
 printf '1,2,3,4\na,b,c,d\n' | sed 's/,/-/'
 
 printf '1,2,3,4\na,b,c,d\n' | sed 's/,/-/g'
 
+## Editing file input
+
 cat greeting.txt
 
 sed 's/day/weekend/' greeting.txt

diff --git a/code_snippets/Processing_lines_bounded_by_distinct_markers.sh b/code_snippets/Processing_lines_bounded_by_distinct_markers.sh
@@ -1,3 +1,5 @@
+## Uniform markers
+
 cat uniform.txt
 
 sed -n '/start/,/end/p' uniform.txt
@@ -16,12 +18,16 @@ sed '/start/,/end/{/start/!d}' uniform.txt
 
 sed '/start/,/end/{/end/!d}' uniform.txt
 
+## Extracting first or last group
+
 sed -n '/start/,/end/{p; /end/q}' uniform.txt
 
 sed -n '/start/,/end/{//!p; /end/q}' uniform.txt
 
 tac uniform.txt | sed -n '/end/,/start/{p; /start/q}' | tac
 
+## Broken groups
+
 cat log.txt
 
 sed -n '/warning/,/error/p' log.txt