While this confirms my confusion (missing better words here..), I learned some new things allthough most of it was known.
Asdide the fact that 'echo' is both, for some reason I always thought that /bin/echo was the echo used when calling echo, and thus not realized the builtin existed - or that they are different 'code'. How to distinguish between builtin and external util? (e.g. echo) - Unix & Linux Stack Exchange
That I most likley could rely on the bash builtin 'echo' for the use of SWARM.
But none of that sounded certain, so I then I followed a link of the 2nd post (46 up votes) about the standarized commands by PSIX and ended up here: echo
Now, when you go down to the 'Application Usage' section, you'll see this part:
Code:
It is not possible to use echo portably across all POSIX systems unless both -n (as the first argument) and escape sequences are omitted.
The printf utility can be used portably to emulate any of the traditional behaviors of the echo utility as follows (assuming that IFS has its standard value or is unset):
The historic System V echo and the requirements on XSI implementations in this volume of POSIX.1-2017 are equivalent to:
printf "%b\n" "$*"
The BSD echo is equivalent to:
if [ "X$1" = "X-n" ]
then
shift
printf "%s" "$*"
else
printf "%s\n" "$*"
fi
New applications are encouraged to use printf instead of echo.
Now my final question, which of these 2 examples would you recomend?
I have to ask this, because I lack the practical experience of actual daily usage on different systems.
Anyway, I'm going to try this out now.
Lets see which works better as expected.
At least I know now that it wasnt a waste of time preparing $ECHO to use printf, what a relieve!
i made a lot of processes. here is the code:
main()
{
printf("\nEnter K="); scanf("%d",&k);
printf("Enter L="); scanf("%d",&l);
printf("\nFather id=%d\n",getpid());
x=0;
makechild();
sleep(2);
return 1;
}
int makechild()
{
for(q=1;q<=k;q++)
{
if(f=fork())
{
... (5 Replies)
Hi,
I have a shell scripting. This will take 7 digit number in each line and add 7 digit number with next subsequent lines ( normal addition ).
Eg:
0000001
0000220
0001235
0000022
0000023
...........
.........
........
Like this i am having around 1500000 records. After adding... (23 Replies)
Hi I have a problem writing a c program that makes a telnet connection and writes some command.
The shell command is something like this:
------------------------------------------------------------------
>
>telnet 141.111.231.132 3300
ENTER COMMAND: login "<--- I' wirte a command (ex... (5 Replies)
Hi, guys:
I am working on my shell using c. How can I use pipe to implement the following?
ls -l 1>> | grep hellp 1<< 2>> | less 2<<
(the output of ls goes to grep, and the output of grep goes to less)
Thanks
Please use and tags when posting code, data or logs etc. to preserve... (1 Reply)
Hello everyone, I'm in need of some assistance. I'm currently enrolled in an introductory UNIX shell programming course and, well halfway through the semester, we are receiving our first actual assignment. I've somewhat realized now that I've fallen behind, and I'm working to get caught up, but for... (1 Reply)
Hi All,
I am using the below script which has awk command, but it is not returing the expected result. can some pls help me to correct the command.
The below script sample.ksh should give the result if the value of last 4 digits in the variable NM matches with the variable value DAT. The... (7 Replies)
Hi guys,
I need to know how i can ignore Pipe '|' if Pipe is coming as a column in Pipe delimited file
for eg:
file 1:
xx|yy|"xyz|zzz"|zzz|12...
using below awk command
awk 'BEGIN {FS=OFS="|" } print $3
i would get xyz
But i want as :
xyz|zzz to consider as whole column... (13 Replies)
Hello,
I have an ffmpeg bash script which is working nice and
I need to do the same for other sources.
To create new scripts and to deal with multiple bash files sounds not logical. It is a bit hard to manage for me..
I wondered if it was possible to make my input file as variable.
Then I... (1 Reply)
Discussion started by: baris35
1 Replies
LEARN ABOUT CENTOS
echo
ECHO(1P) POSIX Programmer's Manual ECHO(1P)PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the correspond-
ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.
NAME
echo - write arguments to standard output
SYNOPSIS
echo [string ...]
DESCRIPTION
The echo utility writes its arguments to standard output, followed by a <newline>. If there are no arguments, only the <newline> is writ-
ten.
OPTIONS
The echo utility shall not recognize the "--" argument in the manner specified by Guideline 10 of the Base Definitions volume of
IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines; "--" shall be recognized as a string operand.
Implementations shall not support any options.
OPERANDS
The following operands shall be supported:
string A string to be written to standard output. If the first operand is -n, or if any of the operands contain a backslash ( '' ) charac-
ter, the results are implementation-defined.
On XSI-conformant systems, if the first operand is -n, it shall be treated as a string, not an option. The following character sequences
shall be recognized on XSI-conformant systems within any of the arguments:
a
Write an <alert>.
Write a <backspace>.
c
Suppress the <newline> that otherwise follows the final argument in the output. All characters following the 'c' in the arguments
shall be ignored.
f
Write a <form-feed>.
Write a <newline>.
Write a <carriage-return>.
Write a <tab>.
v
Write a <vertical-tab>.
\
Write a backslash character.
num
Write an 8-bit value that is the zero, one, two, or three-digit octal number num.
STDIN
Not used.
INPUT FILES
None.
ENVIRONMENT VARIABLES
The following environment variables shall affect the execution of echo:
LANG Provide a default value for the internationalization variables that are unset or null. (See the Base Definitions volume of
IEEE Std 1003.1-2001, Section 8.2, Internationalization Variables for the precedence of internationalization variables used to
determine the values of locale categories.)
LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables.
LC_CTYPE
Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as opposed to
multi-byte characters in arguments).
LC_MESSAGES
Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error.
NLSPATH
Determine the location of message catalogs for the processing of LC_MESSAGES .
ASYNCHRONOUS EVENTS
Default.
STDOUT
The echo utility arguments shall be separated by single <space>s and a <newline> shall follow the last argument. Output transformations
shall occur based on the escape sequences in the input. See the OPERANDS section.
STDERR
The standard error shall be used only for diagnostic messages.
OUTPUT FILES
None.
EXTENDED DESCRIPTION
None.
EXIT STATUS
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
CONSEQUENCES OF ERRORS
Default.
The following sections are informative.
APPLICATION USAGE
It is not possible to use echo portably across all POSIX systems unless both -n (as the first argument) and escape sequences are omitted.
The printf utility can be used portably to emulate any of the traditional behaviors of the echo utility as follows (assuming that IFS has
its standard value or is unset):
* The historic System V echo and the requirements on XSI implementations in this volume of IEEE Std 1003.1-2001 are equivalent to:
printf "%b
" "$*"
* The BSD echo is equivalent to:
if [ "X$1" = "X-n" ]
then
shift
printf "%s" "$*"
else
printf "%s
" "$*"
fi
New applications are encouraged to use printf instead of echo.
EXAMPLES
None.
RATIONALE
The echo utility has not been made obsolescent because of its extremely widespread use in historical applications. Conforming applications
that wish to do prompting without <newline>s or that could possibly be expecting to echo a -n, should use the printf utility derived from
the Ninth Edition system.
As specified, echo writes its arguments in the simplest of ways. The two different historical versions of echo vary in fatally incompati-
ble ways.
The BSD echo checks the first argument for the string -n which causes it to suppress the <newline> that would otherwise follow the final
argument in the output.
The System V echo does not support any options, but allows escape sequences within its operands, as described for XSI implementations in
the OPERANDS section.
The echo utility does not support Utility Syntax Guideline 10 because historical applications depend on echo to echo all of its arguments,
except for the -n option in the BSD version.
FUTURE DIRECTIONS
None.
SEE ALSO
printf
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE
and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained
online at http://www.opengroup.org/unix/online.html .
IEEE /The Open Group 2003 ECHO(1P)
03-13-2020
