How to remove newline character if it is the only character in the entire file.?

Login or Register to Ask a Question and Join Our Community

How to remove newline character if it is the only character in the entire file.?

Tags

character, file, newline, remove, shell scipting, shell scripts, unix

Login to Discuss or Reply to this Discussion in Our Community

Top Forums Shell Programming and Scripting How to remove newline character if it is the only character in the entire file.?

01-27-2019

Registered User

3, 0

Join Date: Jan 2019

Last Activity: 17 February 2019, 5:04 AM EST

Posts: 3

Thanks Given: 3

Thanked 0 Times in 0 Posts

How to remove newline character if it is the only character in the entire file.?

I have a file which comes every day and the file data look's as below.

Code:

Vi abc.txt

Code:

a|b|c|d\n
a|g|h|j\n

Some times we receive the file with only a new line character in the file like

Code:

vi abc.txt

Code:

\n

We need to handle the shell script such a way that if the entire file contains only a new line character then remove the new line character else don't touch the file .

Moderator's Comments:

Mod Comment

Please select text before pressing the code tags button!

Last edited by Scrutinizer; 01-27-2019 at 03:09 PM..

rak Kundra

View Public Profile for rak Kundra

Find all posts by rak Kundra

01-27-2019

Moderator

12,296, 3,792

Join Date: Nov 2008

Last Activity: 1 January 2021, 1:47 AM EST

Location: Amsterdam

Posts: 12,296

Thanks Given: 679

Thanked 3,792 Times in 3,282 Posts

Do you mean a literal newline character, or the two characters

Code:

\n

?

If the former, try:

Code:

awk NF oldfile > new file

--
How big are the files?

This User Gave Thanks to Scrutinizer For This Post:

Scrutinizer

View Public Profile for Scrutinizer

Find all posts by Scrutinizer

01-27-2019

Registered User

489, 285

Join Date: Nov 2018

Last Activity: 30 October 2021, 10:47 AM EDT

Location: undefined

Posts: 489

Thanks Given: 382

Thanked 285 Times in 215 Posts

Code:

#!/bin/bash
file="file.log"
if ! grep -q "[[:print:]]" $file; then
        >$file
fi

This User Gave Thanks to nezabudka For This Post:

nezabudka

View Public Profile for nezabudka

Find all posts by nezabudka

01-27-2019

Registered User

3, 0

Join Date: Jan 2019

Last Activity: 17 February 2019, 5:04 AM EST

Posts: 3

Thanks Given: 3

Thanked 0 Times in 0 Posts

The fie size is 1byte .

rak Kundra

View Public Profile for rak Kundra

Find all posts by rak Kundra

01-27-2019

Registered User

15,129, 5,008

Join Date: Jul 2012

Last Activity: 4 May 2020, 4:31 PM EDT

Location: Aachen, Germany

Posts: 15,129

Thanks Given: 735

Thanked 5,008 Times in 4,483 Posts

Provided your system (which you fail to mention, btw) has the stat command available, try

Code:

[ $(stat -c%s "$file") = 1 ] && >"$file"

This User Gave Thanks to RudiC For This Post:

RudiC

View Public Profile for RudiC

Find all posts by RudiC

01-27-2019

Registered User

3, 0

Join Date: Jan 2019

Last Activity: 17 February 2019, 5:04 AM EST

Posts: 3

Thanks Given: 3

Thanked 0 Times in 0 Posts

Quote:

Originally Posted by nezabudka

Code:

#!/bin/bash
file="file.log"
if ! grep -q "[[:print:]]" $file; then
        >$file
fi

Thanks for the response . This works for me can you explain me how it actually works.

rak Kundra

View Public Profile for rak Kundra

Find all posts by rak Kundra

01-27-2019

Registered User

489, 285

Join Date: Nov 2018

Last Activity: 30 October 2021, 10:47 AM EDT

Location: undefined

Posts: 489

Thanks Given: 382

Thanked 285 Times in 215 Posts

Check if the file contains printable characters
grep -q "[[:print:]]" $file;
if not if ! truncated to zero >$file
I apologize for the not quite detailed answer, I just learn English

nezabudka

View Public Profile for nezabudka

Find all posts by nezabudka

Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. UNIX for Beginners Questions & Answers

Remove newline character from column spread over multiple lines in a file

Hi, I came across one issue recently where output from one of the columns of the table from where i am creating input file has newline characters hence, record in the file is spread over multiple lines. Fields in the file are separated by pipe (|) delimiter. As header will never have newline...

2. Shell Programming and Scripting

Remove last newline character..

Hi all.. I have a text file which looks like below: abcd efgh ijkl (blank space) I need to remove only the last (blank space) from the file. When I try wc -l the file name,the number of lines coming is 3 only, however blank space is there in the file. I have tried options like...

3. Shell Programming and Scripting

Remove newline character between two delimiters

hi i am having delimited .dat file having content like below. test.dat(5 line of records) ====== PT2~Stag~Pt2 Stag Test. Updated~PT2 S T~Area~~UNCEF R20~~2012-05-24 ~2014-05-24~~ PT2~Stag y~Pt2 Stag Test. Updated~PT2 S T~Area~METR~~~2012-05-24~2014-05-24~~test PT2~Pt2 Stag Test~~PT2 S...

4. Shell Programming and Scripting

How to check newline character in file?

Hi All, I have file with only one record,always be only one record. as like below. if that line contains newline end of the line..no need to add, if not just add the new line character. END OF FILE. ROW COUNT: 7 Please help me.. Thanks,

5. Shell Programming and Scripting

Remove newline character or join the broken record

Hi, I have a very huge file, around 1GB of data. I want to remove the newline characters in the file but not preceded by the original end delimiter {} sample data will look like this 1234567 abcd{} 1234sssss as67 abcd{} 12dsad3dad 4sdad567 abcdsadd{} this should look like this...

6. Shell Programming and Scripting

Remove \n <newline> character inside the records.

Hi, In my file, I have '\n' characters inside a single record. Because of this, a single records appears in many lines and looks like multiple records. In the below file. File 1 ==== 1,nmae,lctn,da\n t 2,ghjik,o\n ut,de\n fk Expected output after the \n removed File 2 =====...

7. Shell Programming and Scripting

any savant ? using AWK/SED to remove newline character between two strings : conditional removal

I'd like to remove (do a pattern or precise replacement - this I can handle in SED using Regex ) ---AFTER THE 1ST Occurrence ( i.e. on the 2nd occurrence - from the 2nd to fourth occurance ) of a specific string : type 1 -- After the 1st occurrence of 1 string1 till the 1st occurrence of...

8. Shell Programming and Scripting

Remove newline character conditionally

Hi All, I have 5000 records like this Request_id|Type|Status|Priority|Ticket Submitted Date and Time|Actual Resolved Date and Time|Current Ticket Owner Group|Case final Ticket Owner Group|Customer Severity|Reported Symptom/Request|Component|Hot Topic|Reason for Missed SLA|Current Ticket...

9. Shell Programming and Scripting

To remove the newline character while appending into a file

Hi All, We append the output of a file's size in a file. But a newline character is appended after the variable. Pls help how to clear this. filesize=`ls -l test.txt | awk `{print $5}'` echo File size of test.txt is $filesize bytes >> logfile.txt The output we got is, File size of...

10. Shell Programming and Scripting

How to remove a newline character at the end of filename

Hi All, I have named a file with current date,time and year as follows: month=`date | awk '{print $2}'` date=`date | awk '{print $3}'` year=`date | awk '{print $6}'` time=`date +%Hh_%Mm_%Ss'` filename="test_"$month"_"$date"_"$year"_"$time".txt" > $filename The file is created with a...

Login or Register to Ask a Question