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#1: How to open, lock, write and close a file in ksh

Posted on 2006-01-22 04:40:16 by herbert

I am a beginner in shell scripting.
I have a question regarding file handling in shell script.
There is a perl script as follows:

open (WRITEFILE, ">>/user/test.html");
flock WRITEFILE, LOCK_EX;
print (WRITEFILE "test");
.....
print (WRITEFILE "<BR>");
close WRITEFILE

If I want to change this to ksh script, how can I do it?

open(WRITEFILE, '/user/test.html')
flock WRITEFILE, LOCK_EX
I am not sure of write something into file
close WRITEFILE.

Can anyone help me with this?

Thanks

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#2: Re: How to open, lock, write and close a file in ksh

Posted on 2006-01-22 21:25:35 by Bill Marcum

On 21 Jan 2006 19:40:16 -0800, Herbert
<kang_uni@hotmail.com> wrote:
> I am a beginner in shell scripting.
> I have a question regarding file handling in shell script.
> There is a perl script as follows:
>
> open (WRITEFILE, ">>/user/test.html");
> flock WRITEFILE, LOCK_EX;
> print (WRITEFILE "test");
> ....
> print (WRITEFILE "<BR>");
> close WRITEFILE
>
> If I want to change this to ksh script, how can I do it?
>
> open(WRITEFILE, '/user/test.html')
"open" and "close" commands are usually not needed in shell scripts,
but when they are needed, files are opened and closed with redirection
commands like "exec >/usr/test.html" or "exec >&-"

> flock WRITEFILE, LOCK_EX
There is a flock command, but it is rarely included in Unix/Linux
distributions. In shell scripts, one usually uses a lock file or
directory, with the assumption that other scripts will test that before
writing the file.

until mkdir lock_dir; do sleep 1; done

> I am not sure of write something into file

Depending on the application:
echo something > $WRITEFILE
echo something >> $WRITEFILE
or
sed 's/oldstring/newstring/' $WRITEFILE > tempfile
mv tempfile $WRITEFILE



--
<james> abuse me. I'm so lame I sent a bug report to
debian-devel-changes

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#3: Re: How to open, lock, write and close a file in ksh

Posted on 2006-01-23 01:10:45 by herbert

Bill Marcum
Jan 22, 4:25 pm show options

Newsgroups: comp.unix.shell
From: Bill Marcum <bmar...@iglou.com> - Find messages by this author
Date: Sun, 22 Jan 2006 15:25:35 -0500
Local: Sun, Jan 22 2006 4:25 pm
Subject: Re: How to open, lock, write and close a file in ksh
Reply | Reply to Author | Forward | Print | Individual Message | Show
original | Report Abuse

On 21 Jan 2006 19:40:16 -0800, Herbert


<kang_...@hotmail.com> wrote:
> I am a beginner in shell scripting.
> I have a question regarding file handling in shell script.
> There is a perl script as follows:

> open (WRITEFILE, ">>/user/test.html");
> flock WRITEFILE, LOCK_EX;
> print (WRITEFILE "test");
> ....
> print (WRITEFILE "<BR>");
> close WRITEFILE


> If I want to change this to ksh script, how can I do it?


> open(WRITEFILE, '/user/test.html')



"open" and "close" commands are usually not needed in shell scripts,
but when they are needed, files are opened and closed with
redirection
commands like "exec >/usr/test.html" or "exec >&-"


> flock WRITEFILE, LOCK_EX


There is a flock command, but it is rarely included in Unix/Linux
distributions. In shell scripts, one usually uses a lock file or
directory, with the assumption that other scripts will test that before

writing the file.

until mkdir lock_dir; do sleep 1; done

> I am not sure of write something into file

Depending on the application:
echo something > $WRITEFILE
echo something >> $WRITEFILE
or
sed 's/oldstring/newstring/' $WRITEFILE > tempfile
mv tempfile $WRITEFILE

-----------
Thanks for the reply but I don't understand the file lock stuff in your
reply.

until mkdir lock_dir; do sleep 1; done

How do I lock '/user/test.html' file? Can you please explain it again?

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#4: Re: How to open, lock, write and close a file in ksh

Posted on 2006-01-23 09:11:21 by Stephane CHAZELAS

2006-01-21, 19:40(-08), Herbert:
> I am a beginner in shell scripting.
> I have a question regarding file handling in shell script.
> There is a perl script as follows:
>
> open (WRITEFILE, ">>/user/test.html");
> flock WRITEFILE, LOCK_EX;
> print (WRITEFILE "test");
> ....
> print (WRITEFILE "<BR>");
> close WRITEFILE
>
> If I want to change this to ksh script, how can I do it?
>
> open(WRITEFILE, '/user/test.html')
> flock WRITEFILE, LOCK_EX
> I am not sure of write something into file
> close WRITEFILE.
>
> Can anyone help me with this?
[...]

You don't want to do it like that. A shell is not a programming
language, you have to think differently, you can't translate
word to word from another language.

--
Stéphane

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