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UNIX for Dummies Questions & Answers
Creating a file / /dev/null
Post 41800 by 435 Gavea on Tuesday 14th of October 2003 11:12:50 PM
10-15-2003
Creating a file / /dev/null
First of all, hello there cOmMuNity ! 
Well, I've got two basic questions:
1) In how many ways it's possible to create a file ?
I know one manner using "touch", other typing something like echo "" > file ...
The fact is that I need to overwrite the file if it exists, and touch isn't capable of doing this (actually, touch isn't that suitable for creating files, is it ? as it's destined to change the access date and time of a file...). So, is the echo "" > file the most elegant way for this purpose ?
2) What is exactly the /dev/null... It isn't the same thing as a NULL value, is it ?
Suppose I've chosen to create a file by the echo "" > file method.
The file starts with a blank line. To avoid this, I've seen
cat /dev/null > file
Is this again the only way ?
I heard also that I could use the -n option of echo, which removes the newline character...
It would be something like echo -n "" > file
It should work out.
Well, that's all for now.
Thank you anyway !!!
435 Gavea - bRaZiL - tHE HEll iS hERe !
Well, I've got two basic questions:
1) In how many ways it's possible to create a file ?
I know one manner using "touch", other typing something like echo "" > file ...
The fact is that I need to overwrite the file if it exists, and touch isn't capable of doing this (actually, touch isn't that suitable for creating files, is it ? as it's destined to change the access date and time of a file...). So, is the echo "" > file the most elegant way for this purpose ?
2) What is exactly the /dev/null... It isn't the same thing as a NULL value, is it ?
Suppose I've chosen to create a file by the echo "" > file method.
The file starts with a blank line. To avoid this, I've seen
cat /dev/null > file
Is this again the only way ?
I heard also that I could use the -n option of echo, which removes the newline character...
It would be something like echo -n "" > file
It should work out.
Well, that's all for now.
Thank you anyway !!!
435 Gavea - bRaZiL - tHE HEll iS hERe !
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LEARN ABOUT LINUX
shtool-echo
SHTOOL-ECHO.TMP(1) GNU Portable Shell Tool SHTOOL-ECHO.TMP(1) NAME
shtool-echo - GNU shtool echo(1) extensional command SYNOPSIS
shtool echo [-n|--newline] [-e|--expand] string DESCRIPTION
shtool echo is an echo(1) style command which prints string to stdout and optionally provides special expansion constructs (terminal bold mode, environment details, date, etc) and newline control. The trick of this command is that it provides a portable -n option and hides the gory details needed to find out the environment details under option -e. OPTIONS
The following command line options are available. -n, --newline By default, output is written to stdout followed by a "newline" (ASCII character 0x0a). If option -n is used, this newline character is omitted. -e, --expand If option -e is used, string can contain special "%x" constructs which are expanded before the output is written. Currently the following constructs are recognized: %B switch terminal mode to bold display mode. %b switch terminal mode back to normal display mode. %u the current user name. %U the current user id (numerical). %g the current group name. %G the current group id (numerical). %h the current hostname (without any domain extension). %d the current domain name. %D the current day of the month. %M the current month (numerical). %m the current month name. %Y the current year. EXAMPLE
# shell script shtool echo -n -e "Enter your name [%B%u%b]: "; read name shtool echo -e "Your Email address might be %u@%h%d" shtool echo -e "The current date is %D-%m-%Y" HISTORY
The GNU shtool echo command was originally written by Ralf S. Engelschall <rse@engelschall.com> in 1998 for Website META Language (WML) under the name buildinfo. It was later taken over into GNU shtool. SEE ALSO
shtool(1), echo(1). 18-Jul-2008 shtool 2.0.8 SHTOOL-ECHO.TMP(1)