03-14-2002
i don't understand the "sort" command
i have been trying to understand this chapter titled "Searching for Files and Text" for a few weeks now.
unfortunately, this chapter is one of those things, that no matter how hard you try and how long you try for, you are incapable of understanding (at least in my case)
this entire chapter, grep and it's derivatives and the sort command have been extremely frustrating.
i am hung up on the sort command more so than the others, but there are certain features that are especially difficult to understand.
this is what the book says about the sort command:
sort -options filenames(s)
the following two options are killing me:
-n performs a numeric sort.
(+|-)n begins (+n) or ends (-n) the sort with the field following the n
field
consider the following two examples, that have 8 columns (do columns=fields ?):
sort -rn +4 list -o num.list
sort -rn -3 list -o num2.list
sort +5n list -o update.list
first i would like some clarification with the (+|-)n option.
in the first example, the +4 says that we start counting from the 5th field (5th field because we start counting from 0, not 1 right?)... so when we count, we use fields 5,6,7 right?
in the second example, the -3 says we start counting from the 4th field backwards right? so 3,2,1,0?
next, i'm confused with what I see with the first two examples and the last. I notice that in the first two examples the +/- numbers (+4 and -3) are isolated options, but in the last example, +5n, the two options I mentioned earlier are combined. I don't understand why this is done, or what it means. shouldn't it be +5 -n instead of +5n? is +5 -n different from +5n?
can anyone please help reduce my confusion with this command?
10 More Discussions You Might Find Interesting
1. UNIX for Dummies Questions & Answers
when ever i type it in it always looks like so
echo $file | sed 's/~/\
/g'
how can i get it on one line? (6 Replies)
Discussion started by: Optimus_P
6 Replies
2. Solaris
Hello experts,
I am using SunFire T200.
When I start reading the mail with "mail" command it comes older mail first.
From MAILER-DAEMON Sat Mar 28 06:02:48 2009
Return-Path: <MAILER-DAEMON@emarn1>
Received: from localhost (localhost)
....
....
I want to see the most recent mail... (1 Reply)
Discussion started by: thepurple
1 Replies
3. Shell Programming and Scripting
Hi all,
I have a script with those two lines :
test -f $PWD/mysetup.txt
. $PWD/mysetup.txt
I understand the first one, but could anyone explain me the role of the second one? All the thing I find is the usage :
Thx in advance (3 Replies)
Discussion started by: Moumou
3 Replies
4. Red Hat
Hi Friends,
I am really confused with the output of "free" command on redhat linux.
I can see caching and buffer output on two different areas on the output.
Please let me know whats the difference of these two different outputs.
Here I am pasting the command output of my server.
# free... (3 Replies)
Discussion started by: arumon
3 Replies
5. Shell Programming and Scripting
I need to sort the following file by the rhdiskpower devices in the last column:
Total_MB Free_MB OS_MB Name Failgroup Library Label UDID Product Redund Path
1024 851 1024 OCRVOT1_0000 OCRVOT1_0000 System UNKNOWN ... (3 Replies)
Discussion started by: wjssj
3 Replies
6. Shell Programming and Scripting
Hi,
I have line in input file as below:
3G_CENTRAL;INDONESIA_(M)_TELKOMSEL;SPECIAL_WORLD_GRP_7_FA_2_TELKOMSEL
My expected output for line in the file must be :
"1-Radon1-cMOC_deg"|"LDIndex"|"3G_CENTRAL|INDONESIA_(M)_TELKOMSEL"|LAST|"SPECIAL_WORLD_GRP_7_FA_2_TELKOMSEL"
Can someone... (7 Replies)
Discussion started by: shis100
7 Replies
7. Shell Programming and Scripting
Hello Everybody :) !!!. i have question in mind, is it possible to sort a list of hexadecimal numbers using "sort" command? (9 Replies)
Discussion started by: Kesavan
9 Replies
8. UNIX for Dummies Questions & Answers
I am going through the Unix Made Easy second edition book by John Muster. So far it's been very informative and I can tell it may be a bit out of date.
In one of the exercises it talks about the "sort" command and using it to sort column's of data etc. The "sort" command has changed a bit and... (1 Reply)
Discussion started by: budfoxcat
1 Replies
9. UNIX for Dummies Questions & Answers
How to use "mailx" command to do e-mail reading the input file containing email address, where column 1 has name and column 2 containing “To” e-mail address
and column 3 contains “cc” e-mail address to include with same email.
Sample input file, email.txt
Below is an sample code where... (2 Replies)
Discussion started by: asjaiswal
2 Replies
10. UNIX for Beginners Questions & Answers
Hi All,
I have 2 pipe delimited files viz., file_old and file_new. I'm trying to compare these 2 files, and extract all the different rows between them into a new_file.
comm -3 < sort file_old < sort file_new > new_file
I am getting the below error:
-ksh: sort: cannot open
But if I do... (7 Replies)
Discussion started by: njny
7 Replies
JOIN(1) BSD General Commands Manual JOIN(1)
NAME
join -- relational database operator
SYNOPSIS
join [-a file_number | -v file_number] [-e string] [-o list] [-t char] [-1 field] [-2 field] file1 file2
DESCRIPTION
The join utility performs an ``equality join'' on the specified files and writes the result to the standard output. The ``join field'' is
the field in each file by which the files are compared. The first field in each line is used by default. There is one line in the output
for each pair of lines in file1 and file2 which have identical join fields. Each output line consists of the join field, the remaining
fields from file1 and then the remaining fields from file2.
The default field separators are tab and space characters. In this case, multiple tabs and spaces count as a single field separator, and
leading tabs and spaces are ignored. The default output field separator is a single space character.
Many of the options use file and field numbers. Both file numbers and field numbers are 1 based, i.e., the first file on the command line is
file number 1 and the first field is field number 1. The following options are available:
-a file_number
In addition to the default output, produce a line for each unpairable line in file file_number.
-e string
Replace empty output fields with string.
-o list
The -o option specifies the fields that will be output from each file for each line with matching join fields. Each element of list
has either the form file_number.field, where file_number is a file number and field is a field number, or the form '0' (zero), repre-
senting the join field. The elements of list must be either comma (',') or whitespace separated. (The latter requires quoting to
protect it from the shell, or, a simpler approach is to use multiple -o options.)
-t char
Use character char as a field delimiter for both input and output. Every occurrence of char in a line is significant.
-v file_number
Do not display the default output, but display a line for each unpairable line in file file_number. The options -v 1 and -v 2 may be
specified at the same time.
-1 field
Join on the field'th field of file1.
-2 field
Join on the field'th field of file2.
When the default field delimiter characters are used, the files to be joined should be ordered in the collating sequence of sort(1), using
the -b option, on the fields on which they are to be joined, otherwise join may not report all field matches. When the field delimiter char-
acters are specified by the -t option, the collating sequence should be the same as sort(1) without the -b option.
If one of the arguments file1 or file2 is '-', the standard input is used.
EXIT STATUS
The join utility exits 0 on success, and >0 if an error occurs.
COMPATIBILITY
For compatibility with historic versions of join, the following options are available:
-a In addition to the default output, produce a line for each unpairable line in both file1 and file2.
-j1 field
Join on the field'th field of file1.
-j2 field
Join on the field'th field of file2.
-j field
Join on the field'th field of both file1 and file2.
-o list ...
Historical implementations of join permitted multiple arguments to the -o option. These arguments were of the form
file_number.field_number as described for the current -o option. This has obvious difficulties in the presence of files named 1.2.
These options are available only so historic shell scripts do not require modification and should not be used.
SEE ALSO
awk(1), comm(1), paste(1), sort(1), uniq(1)
STANDARDS
The join command conforms to IEEE Std 1003.1-2001 (``POSIX.1'').
BSD
July 5, 2004 BSD