Adding tab to system()

[blarneyme]

Need to add a tab to a string inside system().

For example:

system("echo x.x.x.x\t > file.txt");

But the \t is only adding a space to file.txt.

I've also tried setting '$t = '\t'; but that also only prints a space:

system("echo x.x.x.x${t} > file.txt");

 

[mikrom]

Hi,
If I try the following

[url=http://perldoc.perl.org/functions/use.html][black][b]use[/b][/black][/url] [green]strict[/green][red];[/red]
[black][b]use[/b][/black] [green]warnings[/green][red];[/red]

[url=http://perldoc.perl.org/functions/my.html][black][b]my[/b][/black][/url] [blue]$cmd[/blue]=[red]"[/red][purple]echo x.x.x.x[purple][b]\t[/b][/purple] > file.txt[/purple][red]"[/red][red];[/red]
[url=http://perldoc.perl.org/functions/print.html][black][b]print[/b][/black][/url] [red]"[/red][purple][purple][b]\$[/b][/purple]cmd = [blue]$cmd[/blue][purple][b]\n[/b][/purple][/purple][red]"[/red][red];[/red]

[gray][i]# execute command[/i][/gray]
[black][b]my[/b][/black] [blue]$rc[/blue]=[url=http://perldoc.perl.org/functions/system.html][black][b]system[/b][/black][/url][red]([/red][blue]$cmd[/blue][red])[/red][red];[/red]
[black][b]print[/b][/black] [red]"[/red][purple][purple][b]\$[/b][/purple]rc = [blue]$rc[/blue][purple][b]\n[/b][/purple][/purple][red]"[/red]

[tt]------------------------------------------------------------
Pragmas (perl 5.10.0) used :
[ul]
[li]strict - Perl pragma to restrict unsafe constructs[/li]
[li]warnings - Perl pragma to control optional warnings[/li]
[/ul]
[/tt]
then after viewing the created file file.txt in HEX I see

[COLOR=#ff00ff]0000000[/color][COLOR=#008080]:[/color] 782e 782e 782e 7809 200d 0a         [COLOR=#804040][b]     x[/b][/color].[COLOR=#804040][b]x[/b][/color].[COLOR=#804040][b]x[/b][/color].[COLOR=#804040][b]x[/b][/color].[COLOR=#804040][b] [/b][/color]..

Also you see \t i.e. 09H (0x09) the horizontal tab character is in the file. but followed by space i.e. 20H (0x20) - see the ASCII Chart

 

[feherke]

Hi

If that runs on Unix or Unix-like system, I would be concerned by the shell issue part - the [tt]\t[/tt] is enumerated in [tt]IFS[/tt] so will be treated as parameter separator when the word splitting is performed.

[b]my[/b] [navy]$cmd[/navy][teal]=[/teal][green][i]"echo [highlight]'[/highlight]x.x.x.x\t[highlight]'[/highlight] > file.txt"[/i][/green][teal];[/teal]

[gray]# or[/gray]

[b]my[/b] [navy]$cmd[/navy][teal]=[/teal][green][i]"echo [highlight]\"[/highlight]x.x.x.x\t[highlight]\"[/highlight] > file.txt"[/i][/green][teal];[/teal]

mikrom, your code gives me this file :

[blue]master #[/blue] od -xc file.txt 
0000000    2e78    2e78    2e78    0a78
          x   .   x   .   x   .   x  \n
0000010

With my suggestion the file becomes this :

[blue]master #[/blue] od -xc file.txt 
0000000    2e78    2e78    2e78    0978    000a
          x   .   x   .   x   .   x  \t  \n
0000011

And I think the OP wants the later.

By the way, all this happens on Linux with [tt]perl[/tt] 5.10.0 and [tt]bash[/tt] 4.0.28.

Feherke.

http://rootshell.be/~feherke/

 

[mikrom]

Btw, I tried it on Windows, but I wonder why your hex view shows 2e78 and my shows 782e
'x' is hex 78
and
'.' is hex 2e
so 'x.' should be in hex 782e

I tried the od in MSYS on Windows and I got this

$ od -xc file.txt
0000000 2e78 2e78 2e78 0978 0d20 000a
          x   .   x   .   x   .   x  \t      \r  \n  \0
0000013

I wonder why the od command swaps the bytes, but it's OT in this thread

 

[Annihilannic]

In one case it is being interpreted as a 16-bit word on a little-endian system... i.e. the last significant byte is printed first. To avoid confusing myself I usually use od -t x1c, which should look the same on any platform.

$ echo x.x.x.x | od -t x1c
0000000 78 2e 78 2e 78 2e 78 0a
          x   .   x   .   x   .   x  \n
0000010

Annihilannic.

 

[mikrom]

Thanks Annihilannic !

 

[Annihilannic]

s/last/least/

Annihilannic.