Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: Function open() sets errno
Top Forums Programming Function open() sets errno Post 302827523 by JohnGraham on Saturday 29th of June 2013 06:02:29 AM
Old 06-29-2013
Quote:
Originally Posted by rupeshkp728
...we must accompany the check with the return value of the function.
For instance:
Code:
fd = open(...)
if(fd = -1 &&  errno == ...)
{
  ....
}

Kind of, but you seem to just be checking for a specific error. Generally for *NIX system calls:
  • The return value tells you whether there was an error or not, and
  • errno tells you the specific type of error.

Also, be aware that you wrote "fd = -1" not "fd == -1", which is always false - not sure if this is a typo, but make sure you understand why this is an error. I always like to write the constant on the left-hand side of the comparison to try and avoid this sort of thing.

Summing up:

Code:
int fd = open(/* ... */);
if (-1 == fd) {
  // There was an error.
  switch (errno) {
  case EACCESS:
    // Access was denied.
    break;
  // ...etc...
  default:
    // Some unknown/other error.
  }
} else {
  // File opened OK.
}

This User Gave Thanks to JohnGraham For This Post:
rupeshkp728
 

9 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

function to test if file is open

I need to write a function that will work in sh/ksh shell that will test to see if a file has already been opened for writting by another user has anyone written something like this? (3 Replies)
Discussion started by: johnsonbryce
3 Replies

2. Virtualization and Cloud Computing

Clouds (Partially Order Sets) - Streams (Linearly Ordered Sets) - Part 2

timbass Sat, 28 Jul 2007 10:07:53 +0000 Originally posted in Yahoo! CEP-Interest Here is my follow-up note on posets (partially ordered sets) and tosets (totally or linearly ordered sets) as background set theory for event processing, and in particular CEP and ESP. In my last note, we... (0 Replies)
Discussion started by: Linux Bot
0 Replies

3. UNIX and Linux Applications

(lmgrd) Can't open /usr/tmp/.flexlm/lmgrdl.4081, errno: 24

We are a tool vendor and one of our users is getting this error. The user is using several macrovision(FLEXLM) license enabled products including ours. (lmgrd) Can't open /usr/tmp/.flexlm/lmgrdl.4081, errno: 24 At this time, it stops checking out licenses, and will not respond to query's.... (2 Replies)
Discussion started by: return_user
2 Replies

4. Programming

errno

Hey, Can I assume that for certain function calls, errno can never be set to a certain value. More specifically, can I assume that for if the stat function call fails, the errno can never be or "No space left on device." I am assuming that a read function cannot fail because of no space... (5 Replies)
Discussion started by: the_learner
5 Replies

5. UNIX and Linux Applications

Sybase help: Open client, bcp function

To begin: I use Linux The Problem: I need bcp functionality for scripts. Perl modules, such as Sybase:xfer, require ctlib which comes with Sybase Open Client. Talking with Sybase sales reps is an exercise in futility and hate. They know absolutely nothing about their own products and will... (0 Replies)
Discussion started by: Bubnoff
0 Replies

6. Programming

Open function of sys/stat.h

If a process already has the entire file locked for read and write using newstruct.l_type = F_WRLCK; what would happen if another process would try to open it in read only mode using open(filename, O_RDONLY); ? I want to check if the file exists and I want it to work even if another process has... (4 Replies)
Discussion started by: cyler
4 Replies

7. Shell Programming and Scripting

Help !! perl open function

Help Please perl Gurus, I am trying to add ungrouped passengers in a group and I creating a script however it fails on first step only I tried all the options it returns following error. syntax error at junki line 4, near "open " Execution of junki aborted due to compilation errors. ... (2 Replies)
Discussion started by: dynamax
2 Replies

8. Shell Programming and Scripting

Open file function

Hello all, just a quick little part of code i'm writing to check if the file i'm writing too in my automatic process is not being written too manually. #!/bin/bash FUSER=$(/sbin/fuser -s /toto.tmp >/dev/null 2>&1) LSOF=$(/usr/sbin/lsof | grep -q "toto.tmp") PGREP=$(pgrep -f "toto.tmp" >... (6 Replies)
Discussion started by: maverick72
6 Replies

9. HP-UX

Failed to open tape device /dev/rmt/0mn:Device busy (errno = 16)

Hi, Unable to make tape backup, please help. /opt/ignite/bin/make_tape_recovery -a /dev/rmt/?mn -I -v -m tar -x inc_entire=vg00 * Creating local directories for configuration files and archive. ======= 04/25/16 16:28:08 IST Started /opt/ignite/bin/make_tape_recovery. (Mon... (4 Replies)
Discussion started by: anuragr
4 Replies

LEARN ABOUT SUSE

irsend

IRSEND(1)								FSF								 IRSEND(1)

NAME

       irsend - basic LIRC program to send infra-red commands

SYNOPSIS

       irsend [options] DIRECTIVE REMOTE CODE [CODE...]

DESCRIPTION

       Asks the lircd daemon to send one or more CIR (Consumer Infra-Red) commands. This is intended for remote control of electronic devices such
       as TV boxes, HiFi sets, etc.

       DIRECTIVE can be:
	  SEND_ONCE	    - send CODE [CODE ...] once
	  SEND_START	    - start repeating CODE
	  SEND_STOP	    - stop repeating CODE
	  LIST		    - list configured remote items
	  SET_TRANSMITTERS  - set transmitters NUM [NUM ...]
	  SIMULATE	    - simulate IR event

       REMOTE is the name of a remote, as described in the lircd configuration file.

       CODE is the name of a remote control key of REMOTE, as it appears in the lircd configuration file.

       NUM is the transmitter number of the hardware device.

       For the LIST DIRECTIVE, REMOTE and/or CODE can be empty:

	  LIST	 ""    ""   - list all configured remote names
	  LIST REMOTE  ""   - list all codes of REMOTE
	  LIST REMOTE CODE  - list only CODE of REMOTE

       The SIMULATE command only works if it has been explicitly enabled in lircd.

       -h --help
	      display usage summary

       -v --version
	      display version

       -d --device
	      use given lircd socket [/var/run/lirc/lircd]

       -a --address=host[:port]
	      connect to lircd at this address

       -# --count=n
	      send command n times

EXAMPLES

	  irsend LIST DenonTuner ""
	  irsend SEND_ONCE  DenonTuner PROG-SCAN
	  irsend SEND_ONCE  OnkyoAmpli VOL-UP VOL-UP VOL-UP VOL-UP
	  irsend SEND_START OnkyoAmpli VOL-DOWN ; sleep 3
	  irsend SEND_STOP  OnkyoAmpli VOL-DOWN
	  irsend SET_TRANSMITTERS 1
	  irsend SET_TRANSMITTERS 1 3 4
	  irsend SIMULATE "0000000000000476 00 OK TECHNISAT_ST3004S"

FILES

       /etc/lirc/lircd.conf
	      Default lircd configuration file.  It should contain all the remotes, their infra-red codes and the corresponding timing	and  wave-
	      form details.

DIAGNOSTICS

       If lircd is not running (or /var/run/lirc/lircd lacks write permissions) irsend aborts with the following diagnostics:
       "irsend: could not connect to socket"
       "irsend: Connection refused" (or "Permission denied").

SEE ALSO

       The documentation for lirc is maintained as html pages. They are located under html/ in the documentation directory.

       lircd(8), mode2(1), smode2(1), xmode2(1), irrecord(1), irw(1), http://www.lirc.org.

irsend 0.8.7pre1						     May 2010								 IRSEND(1)
All times are GMT -4. The time now is 10:00 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy