I am happily using constructs like the following; I have set -x to show fine distinctions.
Code:
$ exec 4> afile
+ exec
+ 4> afile
$ print -u4 This is the first line in afile
As you can see from the -x expansion, the shell performed the exec command and redirected file descriptor [4] to afile. And yes, the print to fd[4] works just fine.
Now what if I want to use a variable FD, as I would in C or Perl?
Code:
$ fd2=6
$ exec ${fd2}> another
+ exec 6
+ 1> another
ksh: exec: 6: not found
Not the difference: Instead of the blank exec command, it tried to execute a file named 6 and redirected stdout (fd[1]) to "another". This did create the file named "another" but it also closed the shell, as any erroneous exec would do.
So here's my question: Is there a way to open file descriptor via a variable?
By the way, back to fd[4]: Now that I have opened it, I can do this:
Code:
$ fd=4
$ print -u${fd} This is a second line in afile
and it expands to
Code:
+ print -u4 This is a second line in afile
as expected.
And, of course, whatever syntax can be used to open a FD via a variable needs to work to close it i.e. exec ${fd}>&-
I am trying to find a way to check the current status of a file. Such as some cron job processes are dependent on the completion of others. if a file is currently being accessed / modified or simply open state I will wait until it is done being processed before attempting the next process on that... (3 Replies)
I have a requirement to close all the file descriptors from 3 to 1024 for a particular application.
Right now, this is how I do it ..
for ( int i = 3 ; i <= 1024; ++i )
close(i);
The change I am looking at is, I want to do away with the number 1024 and replace it with a constant which... (4 Replies)
Im working on writing a small operating system. I am currently working on implementing dup, dup2, pipe, and close and I need to implement some type of file descriptor table in my PCB.
I was wondering if there is anyone who is familiar with linux/unix implementation of these tables who could... (6 Replies)
I am trying to right a function which uses a file descriptor to write to a log file. The problem is that the on the print statement the file descriptor is called bad. Now when I first open the file and print to it in the f_open function by passing the descriptor to f_print_log all works well,... (6 Replies)
Hello All,
Im opening a file desciptor in perl and sending data using print CMD "$xyz".
is there a limit to the length of the string that I can give to this CMD at a time. (3 Replies)
Hello,
How can i use file descriptor in a script to read 2 files at the same time and extract line 200 from file 1 and line 500 from file 2.
Thanks. (6 Replies)
I am trying to write a script which will only show me the file descriptor count for a process/pid. My script will return me the count only not the whole output. For example, I would like my script to return the output 23 this case, not the whole output.
Can anybody please help me how do I get... (11 Replies)
hello,
Someone can help me with redirectors?
I am writing this script in bash enviroment on Fedora:
exec 4<> /dev/tcp/10.10.11.30/5000 #open socket in input/output
strings<&4 >file.txt &
I send file descriptor 4 to string command to purge data stream from special char while come from... (3 Replies)
Discussion started by: rattoeur
3 Replies
LEARN ABOUT DEBIAN
paps
PAPS(1) General Commands Manual PAPS(1)NAME
paps - UTF-8 to PostScript converter using Pango
SYNOPSIS
paps [options] files...
DESCRIPTION
paps reads a UTF-8 encoded file and generates a PostScript language rendering of the file. The rendering is done by creating outline curves
through the pango ft2 backend.
OPTIONS
These programs follow the usual GNU command line syntax, with long options starting with two dashes (`-'). A summary of options is
included below.
--landscape
Landscape output. Default is portrait.
--columns=cl
Number of columns output. Default is 1.
Please notice this option isn't related to the terminal length as in a "80 culums terminal".
--font=desc
Set the font description. Default is Monospace 12.
--rtl Do right to left (RTL) layout.
--paper ps
Choose paper size. Known paper sizes are legal, letter and A4. Default is A4.
Postscript points
Each postscript point equals to 1/72 of an inch. 36 points are 1/2 of an inch.
--bottom-margin=bm
Set bottom margin. Default is 36 postscript points.
--top-margin=tm
Set top margin. Default is 36 postscript points.
--left-margin=lm
Set left margin. Default is 36 postscript points.
--right-margin=rm
Set right margin. Default is 36 postscript points.
--gutter-width=gw
Set gutter width. Default is 40 postscript points.
--help Show summary of options.
--header
Draw page header for each page.
--markup
Interpret the text as pango markup.
--lpi Set the lines per inch. This determines the line spacing.
--cpi Set the characters per inch. This is an alternative method of specifying the font size.
--stretch-chars
Indicates that characters should be stretched in the y-direction to fill up their vertical space. This is similar to the texttops
behaviour.
AUTHOR
paps was written by Dov Grobgeld <dov.grobgeld@gmail.com>.
This manual page was written by Lior Kaplan <kaplan@debian.org>, for the Debian project (but may be used by others).
April 17, 2006 PAPS(1)
12-28-2011
Variable File Descriptor
