How to extract one column of a csv file

Question

If I have a csv file  is there a quick bash way to print out the contents of only any single column   It is safe to assume that each row has the same number of columns  but each column s content would have different length

User · Answer

Landed here looking to extract from a tab separated file  Thought I would add    cat textfile tsv   cut -f2 -s   Where -f2 extracts the 2  non-zero indexed column  or the second column

User · Answer

yes  cat mycsv csv   cut -d     -f3 will print 3rd column

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You could use GNU Awk  see this article of the user guide  As an improvement to the solution presented in the article  in June 2015   the following gawk command allows double quotes inside double quoted fields  a double quote is marked by two consecutive double quotes      there  Furthermore  this allows empty fields  but even this can not handle multiline fields  The following example prints the 3rd column  via c 3  of textfile csv      bin bash gawk --   BEGIN      FPAT                                            if  substr  c  1  1                      c   substr  c  2  length  c  - 2    Get the text within the two quotes         gsub                c     Normalize double quotes           print  c     c 3  lt   lt  dos2unix  lt textfile csv    Note the use of dos2unix to convert possible DOS style line breaks  CRLF i e    r n   and UTF-16 encoding  with byte order mark  to   n  and UTF-8  without byte order mark   respectively  Standard CSV files use CRLF as line break  see Wikipedia   If the input may contain multiline fields  you can use the following script  Note the use of special string for separating records in output  since the default separator newline could occur within a record   Again  the following example prints the 3rd column  via c 3  of textfile csv      bin bash gawk --   BEGIN      RS   0    Read the whole input file as one record        assume there is no null character in input      FS      Suppose this setting eases internal splitting work      ORS   n     n    Use a special output separator to show borders of a record          nof patsplit  0  a         n                        seps      field 0      for  i 1  i lt  nof  i             field           if  field  c                if  substr a i   1  1                             a i    substr a i   2  length a i   - 2    Get the text within                    the two quotes                  gsub             a i      Normalize double quotes                            print a i                    if  seps i        field 0           c 3  lt   lt  dos2unix  lt textfile csv    There is another approach to the problem  csvquote can output contents of a CSV file modified so that special characters within field are transformed so that usual Unix text processing tools can be used to select certain column  For example the following code outputs the third column   csvquote textfile csv   cut -d     -f 3   csvquote -u   csvquote can be used to process arbitrary large files

User · Answer

I needed proper CSV parsing  not cut   awk and prayer  I m trying this on a mac without csvtool  but macs do come with ruby  so you can do   echo  require  csv   CSV read  new csv   each   data  puts data 34      ruby

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Many answers for this questions are great and some have even looked into the corner cases   I would like to add a simple answer that can be of daily use    where you mostly get into those corner cases  like having escaped commas or commas in quotes etc         FS  Field Separator  is the variable whose value is dafaulted to   space  So awk by default splits at space for any line    So using BEGIN  Execute before taking input  we can set this field to anything we want     awk  BEGIN  FS          print  3     The above code will print the 3rd column in a csv file

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Here is a csv file example with 2 columns  myTooth csv     Date Tooth 2017-01-25 wisdom 2017-02-19 canine 2017-02-24 canine 2017-02-28 wisdom   To get the first column  use   cut -d  -f1 myTooth csv   f stands for Field and d stands for delimiter  Running the above command will produce the following output   Output  Date 2017-01-25 2017-02-19 2017-02-24 2017-02-28   To get the 2nd column only   cut -d  -f2 myTooth csv   And here is the output Output  Tooth wisdom canine canine wisdom incisor   Another use case   Your csv input file contains 10 columns and you want columns 2 through 5 and columns 8  using comma as the separator    cut uses -f  meaning  fields   to specify columns and -d  meaning  delimiter   to specify the separator  You need to specify the latter because some files may use spaces  tabs  or colons to separate columns   cut -f 2-5 8 -d   myvalues csv   cut is a command utility and here is some more examples   SYNOPSIS      cut -b list  -n   file           cut -c list  file           cut -f list  -d delim   -s   file

User · Answer

Been using this code for a while  it is not  quick  unless you count  cutting and pasting from stackoverflow    It uses       and       operators in a loop instead of IFS   It calls  err  and  die   and supports only comma  dash  and pipe as SEP chars  that s all I needed    err      echo    0       Error         gt  amp 2    die      err       exit 1       Return Nth field in a csv string  fields numbered starting with 1 csv fldN     fldN     1    2        Return Nth field in string of fields separated   by SEP  fields numbered starting with 1 fldN             local me  fldN            local sep   1          local fldnum   2          local vals   3          case   sep  in                 -                             die   me  arg1 sep  unsupported separator   sep              esac         case   fldnum  in                  0-9        fldnum  -gt 0        err   me  arg2 fldnum  fldnum must be number greater or equal to 0    return 1                            err   me  arg2 fldnum  fldnum must be number   return 1              esac           -z   vals     amp  amp  err   me  missing arg2 vals  list of   sep  separated values   amp  amp  return 1         fldnum     fldnum - 1           while    fldnum -gt 0     do                 vals    vals   sep                   fldnum     fldnum - 1           done         echo   vals   sep       Example     CSVLINE  example fields with whitespace field3      for fno in   seq 3   do echo field fno    csv fldN  fno   CSVLINE     done field1  example field2  fields with whitespace field3  field3

User · Answer

You can also use while loop  IFS   while read name val  do         echo                                         echo Name    name  done lt itemlst csv

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I wonder why none of the answers so far have mentioned csvkit       csvkit is a suite of command-line tools for converting to and working   with CSV   csvkit documentation  I use it exclusively for csv data management and so far I have not found a problem that I could not solve using cvskit   To extract one or more columns from a cvs file you can use the csvcut utility that is part of the toolbox  To extract the second column use this command   csvcut -c 2 filename in csv  gt  filename out csv    csvcut reference page  If the strings in the csv are quoted  add the quote character with the q option    csvcut -q     -c 2 filename in csv  gt  filename out csv    Install with pip install csvkit or sudo apt install csvkit

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csvtool col 2 file csv    where 2 is the column you are interested in  you can also do   csvtool col 1 2 file csv    to do multiple columns

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You could use awk for this  Change   2  to the nth column you want   awk -F             print  2   textfile csv

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First we ll create a basic CSV  dumb one pts   cat  gt  file  a b c d e f g h i k   1 2 3 4 5 6 7 8 9 10   a b c d e f g h i k   1 2 3 4 5 6 7 8 9 10  Then we get the 1st column  dumb one pts    awk -F     print  1   file   a   1   a   1

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The simplest way I was able to get this done was to just use csvtool  I had other use cases as well to use csvtool and it can handle the quotes or delimiters appropriately if they appear within the column data itself   csvtool format    2  n  input csv   Replacing 2 with the column number will effectively extract the column data you are looking for

User · Answer

The other answers work well  but since you asked for a solution using just the bash shell  you can do this   AirBoxOmega   d  cat  gt  file  First we ll create a basic CSV a b c d e f g h i k 1 2 3 4 5 6 7 8 9 10 a b c d e f g h i k 1 2 3 4 5 6 7 8 9 10 a b c d e f g h i k 1 2 3 4 5 6 7 8 9 10 a b c d e f g h i k 1 2 3 4 5 6 7 8 9 10 a b c d e f g h i k 1 2 3 4 5 6 7 8 9 10 a b c d e f g h i k 1 2 3 4 5 6 7 8 9 10   And then you can pull out columns  the first in this example  like so    AirBoxOmega   d  while IFS   read -a csv line do echo    csv line 0    done  lt  file a 1 a 1 a 1 a 1 a 1 a 1   So there s a couple of things going on here     while IFS   - this is saying to use a comma as the IFS  Internal Field Separator   which is what the shell uses to know what separates fields  blocks of text   So saying IFS   is like saying  a b  is the same as  a b  would be if the IFS      which is what it is by default    read -a csv line  - this is saying read in each line  one at a time and create an array where each element is called  csv line  and send that to the  do  section of our while loop do echo    csv line 0    done  lt  file - now we re in the  do  phase  and we re saying echo the 0th element of the array  csv line   This action is repeated on every line of the file  The  lt  file part is just telling the while loop where to read from  NOTE  remember  in bash  arrays are 0 indexed  so the first column is the 0th element     So there you have it  pulling out a column from a CSV in the shell  The other solutions are probably more practical  but this one is pure bash

User · Answer

You can t do it without a full CSV parser

User · Answer

I think the easiest is using csvkit   Gets the 2nd column  csvcut -c 2 file csv  However  there s also csvtool  and probably a number of other csv bash tools out there   sudo apt-get install csvtool  for Debian-based systems   This would return a column with the first row having  ID  in it  csvtool namedcol ID csv file csv  This would return the fourth row  csvtool col 4 csv file csv  If you want to drop the header row   csvtool col 4 csv file csv   sed  1d

[bash] How to extract one column of a csv file

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