topic Re: command problem in Operating System - Linux

command problem

neocosmic — Fri, 25 Apr 2003 05:51:41 GMT

1. what's file descriptor?

2. how can i ensure that a command use only a certain amount of resources when it is excuted?

3.how to check the file contain unprintable characters?

Re: command problem

Balaji N — Fri, 25 Apr 2003 06:30:37 GMT

1. snipped from the open man page.

The open() system call is used to convert a pathname into a file
descriptor (a small, non-negative integer for use in subsequent I/O as
with read, write, etc.). When the call is successful, the file
descriptor returned will be the lowest file descriptor not currently
open for the process. This call creates a new open file, not shared
with any other process. (But shared open files may arise via the
fork(2) system call.) The new file descriptor is set to remain open
across exec functions (see fcntl(2)). The file offset is set to the
beginning of the file.

2. man bash and search for ulimit. it controls resources available for a shell and process started from it.

3. no idea.

hth
-balaji

Re: command problem

Ramkumar Devanathan — Fri, 25 Apr 2003 06:44:10 GMT

Thanks balaji for answering 1. and 2. I was wondering how best to answer these unix theory questions.

for 3.)

# file should give you some details

# strings may be used.

FWIW.

- ramd.

Re: command problem

Balaji N — Fri, 25 Apr 2003 07:17:47 GMT

u r welcome ram.

and fyi, strings prints only printable characters in a file. noway u can know of non-printable chars.

-balaji

Re: command problem

Ramkumar Devanathan — Fri, 25 Apr 2003 07:43:48 GMT

Neocosmic,

Yup, balaji's right. that's why i'd mentioned the word 'use'...

- ramd.

Re: command problem

Clay Davidson — Sat, 26 Apr 2003 09:52:32 GMT

To check for unprintable characters you could try

cat -v >

Then you can search the newfile for funny looking things like ^Z

hth,

clay