Tagged Questions
17
votes
9answers
3k views
How can I write to the second line of a file from the command line?
I have an external program that produces an output file (largish, 20K lines possible).
I need to insert a new line between the existing line 1 and line 2. I've been looking at awk and sed - I use ...
12
votes
9answers
1k views
There must be a better way to replace single newlines only?
I am in the habit of writing one line per sentence because I typically compile things to LaTex, or am writing in some other format where line breaks get ignored. I use a blank line to indicate the ...
9
votes
3answers
342 views
Process last line first using awk
I have a data file that I want to normalize using awk, based on the last datapoint. Therefor, I would like to access the last data point first, to normalize the data, then process normally.
The ...
8
votes
6answers
710 views
Delete lines beginning with #
How do I delete lines beginning with a #, given that there can be whitespace on the left and right of the #?
# Master socket provides access to userdb information. It's typically
8
votes
3answers
2k views
Delete the first n bytes of files
I've got an extreme problem, and all of the solutions I can imagine are complicated. According to my UNIX/Linux experience there must be an easy way.
I want to delete the first 31 bytes of each file ...
7
votes
10answers
495 views
What's a good way to filter a text file to remove empty lines?
I have a .csv file (on a mac) that has a bunch of empty lines, e.g.:
"1", "2", "lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum ...
7
votes
5answers
2k views
Remove comma between the quotes only in a comma delimited file
I have a input file delimited with commas (,). There are some fields enclosed in double quotes that are having a comma in them. Here is the sample row
123,"ABC, DEV 23",345,534.202,NAME
I need to ...
7
votes
6answers
1k views
Is there any alternative to grep's -A -B -C switches (to print few lines before and after )?
grep -A 2 -B 3
prints 2 lines after the grep string and prints 3 lines before.
grep -C 3
prints 3 Lines before and 3 lines after
Unfortunately, the grep I'm using does not support these ...
7
votes
2answers
935 views
A shell script for joining two files
I want to write a shell script that get two files A and B, and get a result like this:
File A:
user_a tel_a addr_a
user_b tel_b addr_b
File B:
process_1 user_a
process_2 user_a
process_3 user_b
...
6
votes
7answers
613 views
Slick one-liner to convert a list like “1: 2, 3, 4, 5” to “1.2, 1.3, 1.4, 1.5”
Let's say I have a file that looks something like this:
23: a, b, c, d
24: b, d, f
25: c, g
and I want to get output like this:
23.a
23.b
23.c
23.d
24.b
24.d
24.f
25.c
25.g
Of course it's not ...
5
votes
7answers
4k views
How to print only last column?
echo -e 'one two three\nfour five six\nseven eight nine'
one two three
four five six
seven eight nine
how can I do some "MAGIC" do get this output?:
three
six
nine
UPDATE:
I don't need it in this ...
5
votes
7answers
248 views
Swapping an unlimited number of columns
I have a file with columns. See below for an example:
a b c ... z
1 2 3 ... 26
I'd like to swap all columns where the 1st becomes the last, the second becomes the one before last...etc..
z y x ...
5
votes
4answers
209 views
How could I simplify this command to only use awk?
awk '/user/ {print $1 }' /etc/userdomains | sed 's/://'
the format of /etc/userdomains is
domain.tld: user
otherdomain.tld: otheruser
5
votes
3answers
12k views
How to use regrex with AWK for string replacement in this example?
Suppose there is some text from a file:
(bookmarks
("Chapter 1 Introduction 1" "#1"
("1.1 Problem Statement and Basic Definitions 23" "#2")
("Exercises 31" "#30")
("Notes and References 42" "#34"))
)
...
5
votes
2answers
304 views
Replacing missing value blank space with zero
I have input.txt tab-delimited text file around 30K lines, I would like to check each row (s1..s30K lines) for missing value (i.e blank space) and fill the missing value with zero value.See out.txt
...
