How can I use as an AWK field separator

Question

Given the following command  echo  quot 1   quot    awk   1  -F  quot   quot   print  1    why does AWK output  1

User · Answer

If you want to do it programatically  you can use the FS variable   echo  1      awk  BEGIN   FS        1    print  1      Note that if you change it in the main loop rather than the BEGIN loop  it takes affect for the next line read in  since the current line has already been split

User · Answer

You have multiple ways to set   as the separator  awk -F    print  1    awk -v FS     print  1    awk   print  1   FS    awk  BEGIN FS  quot   quot    print  1    All of them are equivalent and will return 1 given a sample input  quot 1 2 3 quot     awk -F    print  1    lt  lt  lt   quot 1 2 3 quot  1   awk -v FS     print  1    lt  lt  lt   quot 1 2 3 quot  1   awk   print  1   FS    lt  lt  lt   quot 1 2 3 quot  1   awk  BEGIN FS  quot   quot    print  1    lt  lt  lt   quot 1 2 3 quot  1

User · Answer

You can also use a regular expression as a field separator  The following will print  quot bar quot  by using a regular expression to set the number  quot 10 quot  as a separator  echo  quot foo 10 bar quot    awk -F  0-9  0-9     print  2

User · Answer

-F is an argument to awk itself    echo  1      awk -F      1   print  1   1

User · Answer

Or you can use  echo  quot 1   quot    awk    1  print  1- quot   quot      This is a really funny equation

User · Answer

AWK works as a text interpreter that goes linewise for the whole document and that goes fieldwise for each line  Thus  1   2    n are references to the fields of each line   1 is the first field   2 is the second field  and so on      You can define a field separator by using the  quot -F quot  switch under the command line or within two brackets with  quot FS     quot   Now consider the answer of J  rgen  echo  quot 1   quot    awk -F   quot   quot    1   print  1    Above the field  boundaries are set by  quot   quot  so we have two fields  1 which is  quot 1 quot  and  2 which is the empty space  After comes the regular expression  quot  1  quot  that instructs the filter to output the first field only when the interpreter stumbles upon a line containing such an expression  I mean 1   The output of the  quot echo quot  command is one line that contains  quot 1 quot   so the filter will work    When dealing with the following example  echo  quot 1   quot    awk   1  -F  quot   quot   print  1    The syntax is messy and the interpreter chose to ignore the part F  quot   quot  and switches to the default field splitter which is the empty space  thus outputting  quot 1  quot  as the first field and there will be not a second field  The answer of J  rgen contains the good syntax

User · Answer

There isn t any need to write this much  Just put your desired field separator with the -F option in the AWK command and the column number you want to print segregated as per your mentioned field separator  echo  quot 1   quot    awk -F    print  1   1  echo  quot 1 2 quot    awk -F    print  1   1

User · Answer

quot -F quot  is a command line argument  not AWK syntax  Try   echo  quot 1   quot    awk -F   quot   quot    1   print  1

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