Web hosting e commerce - Chapter 4 . Processing Text 167 In the
Chapter 4 . Processing Text 167 In the The xargs utility is used to feed arguments to another utility at a rate that it can Real World handle. Using this command when it isn t needed won t produce any errors. Modifying Text with Filters Objective 1.3 GNU and Linux Commands Process Text Streams Using Text Processing Filters. Send text files and output streams through text utility filters to modify the output in a useful way. Includes the use of standard unix commands found in the GNU textutils package such as sed, sort, cut, expand, fmt, head, join, nl, od, paste, pr, split, tac, tail, tr, and wc. Perform Searches of Text Files Making Use of Regular Expressions. Includes creating simple regular expressions and using related tools such as grep and sed to perform searches. Linux offers a variety of tools to use for processing and filtering text. These tools enable you to search for data and then manipulate it depending on the tool you use. The tools can be used from the command line or placed in scripts, which are executed to perform the needed tasks. The output is then either sent to standard output, where it can be redirected or piped into another utility, or sent to a file. The flexibility in the input and output of these tools enables you to customize the text for a variety of uses. Regardless of how many filters are run, the original text remains intact. When working with text files you will likely use a pager such as more or less. These utilities are used to display text one page at a time. The cat utility can also be used to display the contents of a text file. These utilities aren t filters but are often helpful when working with them. Sorting lines of a file The sort utility sorts lines of text and displays them to standard output. It is used to sort, merge, and compare lines from files or standard input. This utility is used with the following syntax: sort option filename Table 4-2 lists the options commonly used with the sort utility.
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