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awk（awk） 1.a w K use space as the default domain delimiter, so if To browse the domain space between the text, do not need to specify this option, but if you want to browse such as p a s s w d file, this file in each domain with a colon as a separator, you must specify the -F option, such as: Awk -F:commandsinput-file 2. if you want to print a domain all 5 domains of record, do not need to specify that $1, $2, $3, $4, $5, $0 can be used, which means all the domain. 3. save awk output output in two ways to save the s h e l l a w K script prompt. The easiest way is to use output redirection symbols file name, the following example to redirect the output to a file wow: Awk{print $0}grade.txt wow 4. the use of standard input Before the in-depth explanation of this chapter, first the awk script input method brief introduction. In fact any scripts are from Accept input in standard input. For the operation of this chapter using awk script, script input file format, for example: Belts.awk grade_student.txt Instead of using the following format: Use redirection method: Belts.awk grade2.txt Or pipe method: Grade2.txt |belts.awk Print all records Awk{print $0}grade.txt Awk read each record. Because there is no model, only part of the {print $0} movement (print all records), the It must be enclosed in braces 5. report printing head The print head is placed in the BEGIN information model, because the head print information is defined as an action, must use parentheses. In the awk view the first record before the information was first printed. AwkBEGIN {print name belt\n--------- {print \t $1} $4}grade.txt 6. tail print information The position of the END in the script placed in the main action. AwkBEGIN {print {print $1} END name\n-----} {end-of-report}grade.txt 7. summed up the following rules. In the face of awk error, can find the appropriate: ? to ensure that the entire awk command in single quotes. ? ensure all quotes in ordered pairs. ? ensure action statement with flower