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+====== Read files ======
+**Concepts:**\\
+Read a file //word-by-word//, //line-by-line//, //character-by-character//.
+**Text:**\\
+Implement a program that reads a file which name is passed through the command line. The file must be read //word-by-word//, //line-by-line// and //character-by-character//.
+**Example:**\\
+Given this input file:
+<code txt file.txt>
+w1 w2
+w3
+</code>
+the program has to provide the following output:
+<code bash>
+$ ./read_files.sh file.txt
+WORD: w1
+WORD: w2
+WORD: w3
+LINE: w1 w2
+LINE: w3
+CHAR: w
+CHAR: 1
+CHAR:
+CHAR: w
+CHAR: 2
+CHAR:
+CHAR: w
+CHAR: 3
+CHAR:
+</code>
+**Solution:**\\
+<code bash read_files.sh>
+#!/bin/bash
+# Read a file word-by-word, line-by-line and character-by-character
+# word-by-word
+for i in $(cat $1) ; do
+    echo "WORD: $i"
+done
+#done > file_out.txt  # If I would like to redirect the output on the file "file_out.txt"
+# line-by-line
+while read i ; do
+  echo "LINE: $i"
+done < $1
+#done < $1 > file_out.txt      # If I would like to redirect the output on the file "file_out.txt"
+# character-by-character
+while read -n 1 i ; do
+      echo "CHAR: $i"
+done < $1
+</code>
+**Comments:**\\
+If all the output of the commands in a ''while'' or ''for'' statements has to be redirected into a file, for instance ''file_out.txt'', the following syntax can be used:
+<code bash>
+while read i ; do
+  echo "LINE: $i"
+done < $1 > file_out.txt
+</code>
+In only the output of some commands has to be redirected to standard output, the following code can be used:
+<code bash>
+rm -f file_out.txt
+while read i ; do
+  echo "LINE: $i" >> file_out.txt
+  echo "Not redirected in file"
+done < $1
+</code>

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