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Script to move the first line of a file to the end

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# 1  
Old 12-26-2008
Script to move the first line of a file to the end
I'm rather new to scripting, and despite my attempts at finding/writing a script to do what I need, I have not yet been successful.

I have a file named "list.txt" of arbitrary length with contents in the following format:
Code:
/home/user/Music/file1.mp3
/home/user/Music/file2.mp3
/home/user/Music/file3.mp3
/home/user/Music/file5.txt
/home/user/Music/file7.wav
/home/user/Music/file11.ogg
/home/user/Music/file13.m4a

I would like a script that will change the contents of "list.txt" to:
Code:
/home/user/Music/file2.mp3
/home/user/Music/file3.mp3
/home/user/Music/file5.txt
/home/user/Music/file7.wav
/home/user/Music/file11.ogg
/home/user/Music/file13.m4a
/home/user/Music/file1.mp3

Basically, I need the first line moved to the end. I don't care whether it's in bash, awk, sed, perl, or whatever scripting language as long as it works.
# 2  
Old 12-26-2008
What is your attempt - you should show that first ?

Here is a sample

Code:
awk '{ if ( NR == 1 ) { store=$0 } else { print } }END{ print store }' filename

# 3  
Old 12-26-2008
using Perl:
Code:
# first_to_last.pl
my $file = shift;
open(FH, '<', $file)  or  die "Failed to read file $file : $! \n";
my $first_line      = <FH>;
my @remaining_lines = <FH>;
close(FH);

open(FH, '>', $file)  or  die "Failed to write file $file : $! \n";
print FH @remaining_lines;
print FH $first_line;
close(FH);

run this script as:
Code:
perl first_to_last.pl list.txt

# 4  
Old 12-26-2008
Why do you want to load the entire file into memory ( almost entire except for the first line ). Won't that be enough to store the first line and print the rest as and when its being read?
# 5  
Old 12-26-2008
Code:
awk 'NR==1{store=$0;next}1;END{print store}' file

# 6  
Old 12-26-2008
Quote:
Originally Posted by Yogesh Sawant
using Perl:
Code:
# first_to_last.pl
my $file = shift;
open(FH, '<', $file)  or  die "Failed to read file $file : $! \n";
my $first_line      = <FH>;
my @remaining_lines = <FH>;
close(FH);

open(FH, '>', $file)  or  die "Failed to write file $file : $! \n";
print FH @remaining_lines;
print FH $first_line;
close(FH);

run this script as:
Code:
perl first_to_last.pl list.txt

Thanks. That works exactly as I need it to.



Quote:
Originally Posted by danmero
Code:
awk 'NR==1{store=$0;next}1;END{print store}' file

That does what I need it to, but it outputs the results to the console, whereas I need it to output it back to the file. I tried setting it equal to a variable and outputting that to a file, but that output the contents of the file separated by spaces rather than line breaks.

Here's what I tried:
Code:
#!/bin/bash
var=`awk 'NR==1{store=$0;next}1;END{print store}' list.txt`
echo $var > list.txt

Code:
$ cat ./list.txt
1
2
3
4
5
6
$ ./first_to_last.sh
$ cat ./list.txt
2 3 4 5 6 1

# 7  
Old 12-27-2008
Quote:
Originally Posted by Altay_H
Basically, I need the first line moved to the end. I don't care whether it's in bash, awk, sed, perl, or whatever scripting language as long as it works.

Code:
{
  IFS= read -r line
  cat
  printf "%s\n" "$line"
} < "$FILE" > tempfile && mv tempfile "$FILE"
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