sed, date and /& - Shell Programming and Scripting

sncr24 · #1 01-01-2008

Hi,

Code:

$ echo 1 titi | sed -e "s/1/$(echo \&)/"
1 titi

but

Code:

$ echo 1 titi | sed -e "s/1/$(date \&)/"
date: invalid date `&'
 titi

how can i do for handle '\&' with date ?

Thx

fpmurphy · #2 01-01-2008

What exactly are you trying to achive with this code?

sncr24 · #3 01-19-2008

Use case is not important, this is just one example.

I just wanna use the seed replacement special character & with the date command, like with echo.

fpmurphy · #4 01-19-2008

You are passing an invalid argument to the date utility as in "date 1", hence the error.

Code:

$ echo 1 titi | sed -e "s/1/$(date \&)/"
date: illegal time format
usage: date [-ajnu] [-d dst] [-r seconds] [+format]
       date -b [-ajnu] [-d dst] [-t west] [+format] [[[[[[cc]yy]mm]dd]HH]MM[.SS]
       date [-ajnu] [-d dst] [-t west] [+format] [mmddHHMM[[cc]yy]]
 titi

sncr24 · #5 01-20-2008

fpmurphy, thx for the reply.

With a good argument, that still doesn't work for me.

Code:

echo 01201300 titi | sed -e "s/01201300/$(date \&)/"

date: invalid date `&'
 titi

GNU bash, version 3.2.25(1)-release (x86_64-pc-linux-gnu)

radoulov · #6 01-20-2008

Do you want an output line this?

Code:

$ echo 08150000 titi | sed "s/08150000/$(date &)/"
Fri Aug 15 00:00:08 WEDT 2008 titi

This will change the machine's date

Perderabo · #7 01-20-2008

sncr24, your question does not make sense. That's why we cannot answer it.

Code:

$ echo 1 titi
1 titi
$ echo 1 titi | sed "s/1/&/"
1 titi

Those 2 command lines have the same output because the sed command makes no change to the text. The ampersand represents the matched field. Normally, you might do something like this...

Code:

$ echo 1 titi | sed -e "s/1/=&=&=/"
=1=1= titi
$

Getting back the the original sed command, which already does nothing, you can replace one of the characters in the sed command with an echo statement and that is what you did with

Code:

$ echo 1 titi | sed -e "s/1/$(echo \&)/"
1 titi

This continues to give the same output as a simple "echo 1 titi" but it watses even more time. Replacing the echo statement with an invocation of date is even more strange, but it can be done because "date" can be forced to behave a little bit like "echo".
echo \&
date +\&
both output a single ampersand. So both

Code:

echo 1 titi | sed -e "s/1/$(echo \&)/"
echo 1 titi | sed -e "s/1/$(date  +\&)/"

are ways to construct a sed command that will not do anything. But even though we got date to behave a liitle bit like echo, this won't be possible with all of the other unix commands.

I do not know what you are try to do, but I hope this helps move you toward fufilling your requirements. (Whatever they may be...)

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