在Linux命令行中更改文本文件

Question

I have a big file like this example:

#name   chrom   strand  txStart txEnd   cdsStart    cdsEnd  exonCount   exonStarts  exonEnds    proteinID   alignID
uc001aaa.3  chr1    +   11873   14409   11873   11873   3   11873,12612,13220,  12227,12721,14409,      uc001aaa.3
uc010nxr.1  chr1    +   11873   14409   11873   11873   3   11873,12645,13220,  12227,12697,14409,      uc010nxr.1
uc010nxq.1  chr1    +   11873   14409   12189   13639   3   11873,12594,13402,  12227,12721,14409,  B7ZGX9  uc010nxq.1
uc009vis.3  chr1    -   14361   16765   14361   14361   4   14361,14969,15795,16606,    14829,15038,15942,16765,        uc009vis.3

I want to change the 4th column. each element in each row in column 4 should be replaced by the element in the same row but from column 5. I want to change this element from column5 and put it in the same row but in column 4. the change would be "(element of column5) - 1". I am not so familiar with command line in linux(shell). do you know how I can do that in a single line? here is the expected output:

#name   chrom   strand  txStart txEnd   cdsStart    cdsEnd  exonCount   exonStarts  exonEnds    proteinID   alignID
uc001aaa.3  chr1    +   14408   14409   11873   11873   3   11873,12612,13220,  12227,12721,14409,      uc001aaa.3
uc010nxr.1  chr1    +   14408   14409   11873   11873   3   11873,12645,13220,  12227,12697,14409,      uc010nxr.1
uc010nxq.1  chr1    +   14408   14409   12189   13639   3   11873,12594,13402,  12227,12721,14409,  B7ZGX9  uc010nxq.1
uc009vis.3  chr1    -   16764   16765   14361   14361   4   14361,14969,15795,16606,    14829,15038,15942,16765,        uc009vis.3

Answer 1

awk is a great tool for manipulating files like this. It allows processing a file that consists of records of fields; by default records are defined by lines in the file and fields are separated by spaces. The awk command line to do what you want is:

awk '!/^#/ { $4 = $5 - 1 } { print }' <filename>

An awk program is a sequence of pattern-action pairs. If a pattern is omitted the action is performed for all input records, if an action is omitted (not used in this program) the default action is to print the record. Fields are referenced in an awk program as $n where n is the field number. There are several forms of pattern but the one used here is the negation a regular expression that is matched against the whole record. So this program updates the 4th field to be the value of the 5th field minus 1 but only for lines that do not start with a # to avoid messing up the header. Then for all records (because the pattern is omitted) the record is printed. The pattern-action pairs are evaluated in order so the records is printed after updating the 4th field.

Answer 2

将您的内容保存为awk'{if（NR> 1）{$ 4 = $ 5-1; print $ 0} else {print $ 0}}'a