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

[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

[Bill Marcum]

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

Post by Herbert
I am a beginner in shell scripting.
I have a question regarding file handling in shell script.
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 >&-"

Post by Herbert
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

Post by Herbert
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

[Herbert]

Bill Marcum
Jan 22, 4:25 pm show options

Newsgroups: comp.unix.shell
From: Bill Marcum <***@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

Post by Herbert
I am a beginner in shell scripting.
I have a question regarding file handling in shell script.
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 >&-"

Post by Herbert
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

Post by Herbert
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?

[Stephane CHAZELAS]

Post by Herbert
I am a beginner in shell scripting.
I have a question regarding file handling in shell script.
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.