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awk questions using sort and grep
Post 302921705 by neutronscott on Sunday 19th of October 2014 07:14:57 PM
10-19-2014
question 6 is basically adding a header. you can use a special block called a BEGIN block in awk to to do. for example awk 'BEGIN { print "name\tid"; } 1 { print $0; }' class.txt
You've not shown much work on the rest.
awk works with fields. You seem to understand how to change the field separator. If you want to print every record where column 5 is greater than 30, you'd use something like awk '$5 > 30'
awk code follows the syntax condition { action }. The default condition is 1 (or always true) and the default action is print $0. Thus, the above example is equivalent to awk '$5 > 30 { print $0 }'.
Have a look at man sort and you will see how to sort on certain fields as well. Make sure to use -n for numeric sort where needed.
The questions involving making a directory and moving files shouldn't require awk. awk is a text processor. Unless those files are to be made with certain text or are part of the other questions output... In the shel you'd use mkdir and mv to make a directory and move files, respectively.
You've not shown much work on the rest.
awk works with fields. You seem to understand how to change the field separator. If you want to print every record where column 5 is greater than 30, you'd use something like awk '$5 > 30'
awk code follows the syntax condition { action }. The default condition is 1 (or always true) and the default action is print $0. Thus, the above example is equivalent to awk '$5 > 30 { print $0 }'.
Have a look at man sort and you will see how to sort on certain fields as well. Make sure to use -n for numeric sort where needed.
The questions involving making a directory and moving files shouldn't require awk. awk is a text processor. Unless those files are to be made with certain text or are part of the other questions output... In the shel you'd use mkdir and mv to make a directory and move files, respectively.
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Last edited by Don Cragun; 10-19-2014 at 10:51 PM.. Reason: Add note.
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LEARN ABOUT MINIX
join
JOIN(1) General Commands Manual JOIN(1) NAME
join - relational database operator SYNOPSIS
join [-an] [-e s] [-o list] [-tc] file1 file2 DESCRIPTION
Join forms, on the standard output, a join of the two relations specified by the lines of file1 and file2. If file1 is `-', the standard input is used. File1 and file2 must be sorted in increasing ASCII collating sequence on the fields on which they are to be joined, normally the first in each line. There is one line in the output for each pair of lines in file1 and file2 that have identical join fields. The output line normally con- sists of the common field, then the rest of the line from file1, then the rest of the line from file2. Fields are normally separated by blank, tab or newline. In this case, multiple separators count as one, and leading separators are dis- carded. These options are recognized: -an In addition to the normal output, produce a line for each unpairable line in file n, where n is 1 or 2. -e s Replace empty output fields by string s. -o list Each output line comprises the fields specified in list, each element of which has the form n.m, where n is a file number and m is a field number. -tc Use character c as a separator (tab character). Every appearance of c in a line is significant. SEE ALSO
sort(1), comm(1), awk(1). BUGS
With default field separation, the collating sequence is that of sort -b; with -t, the sequence is that of a plain sort. The conventions of join, sort, comm, uniq, look and awk(1) are wildly incongruous. 7th Edition April 29, 1985 JOIN(1)