edited the remaining chapters

Author: learnbyexample

basename-dirname.html

@@ -45,7 +45,7 @@
 $ basename 'path with spaces/report.log'
 report.log
 
-# trailing slashes will not affect the output
+# one or more trailing slashes will not affect the output
 $ basename /home/learnbyexample/example_files/
 example_files
 </code></pre><p>If there's no leading directory component or if slash alone is the input, the argument will be returned as is after removing any trailing slashes.<pre><code class=language-bash>$ basename filename.txt
@@ -65,13 +65,15 @@
 $ basename -s'.txt' purchases.txt.txt
 purchases.txt
 
-$ basename -s'report' report
+# -s will be ignored if it would have resulted in empty output
+$ basename -s'report' /backups/report
 report
 </code></pre><p>You can also pass the suffix to be removed after the path argument, but the <code>-s</code> option is preferred as it makes the intention clearer and works for multiple path arguments.<pre><code class=language-bash>$ basename example_files/scores.csv .csv
 scores
 </code></pre><h2 id=remove-filename-from-path><a class=header href=#remove-filename-from-path>Remove filename from path</a></h2><p>By default, the <code>dirname</code> command removes the trailing path component (after removing any trailing slashes).<pre><code class=language-bash>$ dirname /home/learnbyexample/example_files/scores.csv
 /home/learnbyexample/example_files
 
+# one or more trailing slashes will not affect the output
 $ dirname /home/learnbyexample/example_files/
 /home/learnbyexample
 </code></pre><h2 id=multiple-arguments><a class=header href=#multiple-arguments>Multiple arguments</a></h2><p>The <code>dirname</code> command accepts multiple path arguments by default. The <code>basename</code> command requires <code>-a</code> or <code>-s</code> (which implies <code>-a</code>) to work with multiple arguments.<pre><code class=language-bash>$ basename -a /backups/jan_2021.tar.gz /home/learnbyexample/report.log
@@ -86,7 +88,7 @@
 $ dirname /home/learnbyexample/example_files/scores.csv ../report/backups/
 /home/learnbyexample/example_files
 ../report
-</code></pre><h2 id=combining-basename-and-dirname><a class=header href=#combining-basename-and-dirname>Combining basename and dirname</a></h2><p>You can use shell features like command substitution to combine the effects of <code>basename</code> and <code>dirname</code> commands.<pre><code class=language-bash># extract the second last component
+</code></pre><h2 id=combining-basename-and-dirname><a class=header href=#combining-basename-and-dirname>Combining basename and dirname</a></h2><p>You can use shell features like command substitution to combine the effects of <code>basename</code> and <code>dirname</code> commands.<pre><code class=language-bash># extract the second last path component
 $ basename $(dirname /home/learnbyexample/example_files/scores.csv)
 example_files
 </code></pre><h2 id=nul-separator><a class=header href=#nul-separator>NUL separator</a></h2><p>Use <code>-z</code> option if you want to use NUL character as the output path separator.<pre><code class=language-bash>

csplit.html

@@ -61,8 +61,8 @@
 10
 
 $ rm xx*
-</code></pre><blockquote><p><img src=./images/info.svg alt=info> As seen in the example above, <code>csplit</code> will also display the number of bytes written for each output file. You can use the <code>-q</code> option to suppress this message.</blockquote><blockquote><p><img src=./images/info.svg alt=info> <img src=./images/warning.svg alt=warning> As mentioned earlier, remove the output files after every illustration.</blockquote><h2 id=split-on-regexp><a class=header href=#split-on-regexp>Split on regexp</a></h2><p>You can also split the input based on a line matching the given regular expression. The output produced will vary based on <code>//</code> or <code>%%</code> being used to surround the regexp.<p>When <code>/regexp/</code> is used, output is similar to the line number based splitting. The first output file will have the input lines <em>before</em> the first occurrence of a line matching the given regexp and the second output file will have the rest of the contents.<pre><code class=language-bash># match a line containing 't' followed by zero or more characters and then 'p'
-# 'toothpaste' matches for this input file
+</code></pre><blockquote><p><img src=./images/info.svg alt=info> As seen in the example above, <code>csplit</code> will also display the number of bytes written for each output file. You can use the <code>-q</code> option to suppress this message.</blockquote><blockquote><p><img src=./images/info.svg alt=info> <img src=./images/warning.svg alt=warning> As mentioned earlier, remove the output files after every illustration.</blockquote><h2 id=split-on-regexp><a class=header href=#split-on-regexp>Split on regexp</a></h2><p>You can also split the input based on a line matching the given regular expression. The output produced will vary based on <code>//</code> or <code>%%</code> delimiters being used to surround the regexp.<p>When <code>/regexp/</code> is used, output is similar to the line number based splitting. The first output file will have the input lines <em>before</em> the first occurrence of a line matching the given regexp and the second output file will have the rest of the contents.<pre><code class=language-bash># match a line containing 't' followed by zero or more characters and then 'p'
+# 'toothpaste' is the only match for this input file
 $ csplit -q purchases.txt '/t.*p/'
 
 $ head xx*
@@ -127,8 +127,8 @@
 
 $ csplit -q purchases.txt '/t.*p/-5'
 csplit: ‘/t.*p/-5’: line number out of range
-</code></pre><h2 id=repeat-split><a class=header href=#repeat-split>Repeat split</a></h2><p>You can perform line number and regexp based split more than once by adding <code>{N}</code> argument after the pattern. Default behavior is same as specifying <code>{0}</code>. Any number greater than zero will result in that many more splits.<pre><code class=language-bash># {1} means split one more time
-# so two splits in total and three output files
+</code></pre><h2 id=repeat-split><a class=header href=#repeat-split>Repeat split</a></h2><p>You can perform line number and regexp based split more than once by adding <code>{N}</code> argument after the pattern. Default behavior examples seen so far is same as specifying <code>{0}</code>. Any number greater than zero will result in that many more splits.<pre><code class=language-bash># {1} means split one time more than the default split
+# so, two splits in total and three output files
 # in this example, split happens on 4th and 8th line numbers
 $ seq 10 | csplit -q - 4 '{1}'
 

expand-unexpand.html

@@ -52,7 +52,7 @@
 # 'αλε' = 6 bytes, \t converts to 2 spaces
 $ printf 'αλε\tπού\n' | expand
 αλε  πού
-</code></pre><p>Here's an example with <code>7</code> and <code>8</code> byte strings before the tab character:<pre><code class=language-bash>$ printf 'deviate\treached\nbackdrop\toverhang\n' | expand
+</code></pre><p>Here's an example with strings of size <code>7</code> and <code>8</code> bytes before the tab character:<pre><code class=language-bash>$ printf 'deviate\treached\nbackdrop\toverhang\n' | expand
 deviate reached
 backdrop        overhang
 </code></pre><p>The <code>expand</code> command also considers backspace characters to determine the number of spaces needed.<pre><code class=language-bash># sample input with a backspace character
@@ -140,7 +140,7 @@
 ^I^Ia       b       c
 
 # input has 4 spaces and a tab character (that expands till 8th column)
-# output will have only the tab character at the start
+# output will have a single tab character at the start
 $ printf '    \ta b\n' | unexpand | cat -T
 ^Ia b
 </code></pre><blockquote><p><img src=./images/info.svg alt=info> The current <code>locale</code> determines which characters are considered as blanks. Also, <code>unexpand</code> will concatenate multiple files passed as input source, so <code>cat</code> will not be needed for such cases.</blockquote><h2 id=unexpand-all-blanks><a class=header href=#unexpand-all-blanks>Unexpand all blanks</a></h2><p>The <code>-a</code> option will allow you to convert all sequences of two or more blanks at tab boundaries. Here's some examples:<pre><code class=language-bash># default unexpand stops at first non-blank character

join.html

@@ -134,7 +134,7 @@
 Raj,ECE,53
 Raj,EEE,88
 Tia,EEE,72
-</code></pre><h2 id=customize-output-field-list><a class=header href=#customize-output-field-list>Customize output field list</a></h2><p>You can use the <code>-o</code> option to customize the fields required in the output and their order. Especially useful when the first field isn't the key. Each output field is specified as file number, followed by a <code>.</code> character and then the field number. You can specify multiple fields separated by a <code>,</code> character. As a special case, you can use <code>0</code> to indicate the key field.<pre><code class=language-bash># output field order is 1st, 2nd and 3rd fields from the first file
+</code></pre><h2 id=customize-output-field-list><a class=header href=#customize-output-field-list>Customize output field list</a></h2><p>You can use the <code>-o</code> option to customize the fields required in the output and their order. Especially useful when the first field isn't the key. Each output field is specified as file number followed by a <code>.</code> character and then the field number. You can specify multiple fields separated by a <code>,</code> character. As a special case, you can use <code>0</code> to indicate the key field.<pre><code class=language-bash># output field order is 1st, 2nd and 3rd fields from the first file
 $ join -t, -1 2 -o 1.1,1.2,1.3 <(sort -t, -k2,2 marks.csv) names.txt
 CSE,Amy,67
 ECE,Raj,53
@@ -174,7 +174,15 @@
 pen NA 2
 soap 3 1
 tshirt 3 NA
-</code></pre><h2 id=set-operations><a class=header href=#set-operations>Set operations</a></h2><p>This section covers whole line set operations you can perform on already sorted input files. Equivalent <code>sort</code> and <code>uniq</code> (if required) solutions will also be mentioned as comments (useful for unsorted inputs). Assume that there are no duplicate lines within an input file.<pre><code class=language-bash># union
+</code></pre><h2 id=set-operations><a class=header href=#set-operations>Set operations</a></h2><p>This section covers whole line set operations you can perform on already sorted input files. Equivalent <code>sort</code> and <code>uniq</code> solutions will also be mentioned as comments (useful for unsorted inputs). Assume that there are no duplicate lines within an input file.<p>These two sorted input files will be used for the examples to follow:<pre><code class=language-bash>$ paste colors_1.txt colors_2.txt
+Blue    Black
+Brown   Blue
+Orange  Green
+Purple  Orange
+Red     Pink
+Teal    Red
+White   White
+</code></pre><p>Here's how you can get <em>union</em> and <em>symmetric difference</em> results. Recall that <code>-t ''</code> will cause entire input line content to be considered as keys.<pre><code class=language-bash># union
 # unsorted input: sort -u colors_1.txt colors_2.txt
 $ join -t '' -a1 -a2 colors_1.txt colors_2.txt
 Black
@@ -197,7 +205,7 @@
 Pink
 Purple
 Teal
-</code></pre><p>The below examples also include the equivalent <code>comm</code> solutions.<pre><code class=language-bash># intersection, same as: comm -12 colors_1.txt colors_2.txt
+</code></pre><p>Here's how you can get <em>intersection</em> and <em>difference</em> results. The equivalent <code>comm</code> solutions for sorted input is also mentioned in the comments.<pre><code class=language-bash># intersection, same as: comm -12 colors_1.txt colors_2.txt
 # unsorted input: sort colors_1.txt colors_2.txt | uniq -d
 $ join -t '' colors_1.txt colors_2.txt
 Blue
@@ -218,7 +226,7 @@
 Brown
 Purple
 Teal
-</code></pre><p>As mentioned before, <code>join</code> will display all the combinations if there are duplicate entries. Here's an example for displaying common lines:<pre><code class=language-bash>$ paste list_1.txt list_2.txt
+</code></pre><p>As mentioned before, <code>join</code> will display all the combinations if there are duplicate entries. Here's an example to show the differences between <code>sort</code>, <code>comm</code> and <code>join</code> solutions for displaying common lines:<pre><code class=language-bash>$ paste list_1.txt list_2.txt
 apple   cherry
 banana  cherry
 cherry  mango

nl.html

@@ -49,7 +49,7 @@
      7  42
      8  1000
 
-# input with empty lines, same as: cat -b
+# example for input with empty lines, same as: cat -b
 $ printf 'apple\n\nbanana\n\ncherry\n' | nl
      1  apple
 
@@ -252,6 +252,6 @@
 5 tea
   soap
 6 tea
-</code></pre><blockquote><p><img src=./images/info.svg alt=info> See <a href=https://learnbyexample.github.io/learn_gnugrep_ripgrep/breere-regular-expressions.html>Regular Expressions</a> chapter from my <strong>GNU grep</strong> ebook if you want to learn about BRE syntax and features.</blockquote></main><nav class=nav-wrapper aria-label="Page navigation"><a rel=prev href=join.html class="mobile-nav-chapters previous"title="Previous chapter"aria-label="Previous chapter"aria-keyshortcuts=Left> <i class="fa fa-angle-left"></i> </a><a rel=next href=wc.html class="mobile-nav-chapters next"title="Next chapter"aria-label="Next chapter"aria-keyshortcuts=Right> <i class="fa fa-angle-right"></i> </a><div style="clear: both"></div></nav></div></div><nav class=nav-wide-wrapper aria-label="Page navigation"><a rel=prev href=join.html class="nav-chapters previous"title="Previous chapter"aria-label="Previous chapter"aria-keyshortcuts=Left> <i class="fa fa-angle-left"></i> </a><a rel=next href=wc.html class="nav-chapters next"title="Next chapter"aria-label="Next chapter"aria-keyshortcuts=Right> <i class="fa fa-angle-right"></i> </a></nav></div><script>
+</code></pre><blockquote><p><img src=./images/info.svg alt=info> See <a href=https://learnbyexample.github.io/learn_gnugrep_ripgrep/breere-regular-expressions.html>Regular Expressions</a> chapter from my <strong>GNU grep</strong> ebook if you want to learn about regexp syntax and features.</blockquote></main><nav class=nav-wrapper aria-label="Page navigation"><a rel=prev href=join.html class="mobile-nav-chapters previous"title="Previous chapter"aria-label="Previous chapter"aria-keyshortcuts=Left> <i class="fa fa-angle-left"></i> </a><a rel=next href=wc.html class="mobile-nav-chapters next"title="Next chapter"aria-label="Next chapter"aria-keyshortcuts=Right> <i class="fa fa-angle-right"></i> </a><div style="clear: both"></div></nav></div></div><nav class=nav-wide-wrapper aria-label="Page navigation"><a rel=prev href=join.html class="nav-chapters previous"title="Previous chapter"aria-label="Previous chapter"aria-keyshortcuts=Left> <i class="fa fa-angle-left"></i> </a><a rel=next href=wc.html class="nav-chapters next"title="Next chapter"aria-label="Next chapter"aria-keyshortcuts=Right> <i class="fa fa-angle-right"></i> </a></nav></div><script>
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