Sponsored Content
Top Forums Shell Programming and Scripting Difference between "Command substitution" and "Process substitution" Post 302268287 by Christoph Spohr on Monday 15th of December 2008 10:20:15 AM
Old 12-15-2008
Hi,

$(...) means execute the command ... and print the output
to the command line.
<(...) and =(...) create a temporary file of the output and
redirect the output of this to the command line.

To understand the difference try:

Code:
diff $(ls) $(ls)

and

Code:
diff <(ls) <(ls)

The first will fail as diff expects input from a file.

HTH Chris
 

9 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

Explain the line "mn_code=`env|grep "..mn"|awk -F"=" '{print $2}'`"

Hi Friends, Can any of you explain me about the below line of code? mn_code=`env|grep "..mn"|awk -F"=" '{print $2}'` Im not able to understand, what exactly it is doing :confused: Any help would be useful for me. Lokesha (4 Replies)
Discussion started by: Lokesha
4 Replies

2. Red Hat

"service" , "process" and " daemon" ?

Friends , Anybody plz tell me what is the basic difference between "service" , "process" and " daemon" ? Waiting for kind reply .. .. (1 Reply)
Discussion started by: shipon_97
1 Replies

3. Shell Programming and Scripting

bash ignores escaped $ and says "bad substitution"

Can someone tell me how to get the version of bash that I am running? I'm running cygwin bash on Windows XP at home and cygwin bash on Vista at work. Is this the version number for bash? $ uname -a CYGWIN_NT-6.0 US-SEA-L3BER9K 1.5.25(0.156/4/2) 2008-06-12 19:34 i686 Cygwin This is the... (2 Replies)
Discussion started by: siegfried
2 Replies

4. Solaris

difference between "root" and "usr" packages

Hi, could someone pls enlighten me on the difference between the "root" package and "usr" package? Like in this example: pkginfo -l SUNWGtku | grep -i desc DESC: GTK - The GIMP Toolkit (Usr) and pkginfo -l SUNWGtkr | grep -i desc DESC: GTK - The GIMP Toolkit (Root)... (6 Replies)
Discussion started by: masloff
6 Replies

5. Shell Programming and Scripting

awk command to replace ";" with "|" and ""|" at diferent places in line of file

Hi, I have line in input file as below: 3G_CENTRAL;INDONESIA_(M)_TELKOMSEL;SPECIAL_WORLD_GRP_7_FA_2_TELKOMSEL My expected output for line in the file must be : "1-Radon1-cMOC_deg"|"LDIndex"|"3G_CENTRAL|INDONESIA_(M)_TELKOMSEL"|LAST|"SPECIAL_WORLD_GRP_7_FA_2_TELKOMSEL" Can someone... (7 Replies)
Discussion started by: shis100
7 Replies

6. Shell Programming and Scripting

perl's substitution operator "s" with file contents?

Please show me how to make substitution over the contents of a file in a perl script. In a perl script, the core part of substitution operation is s/FINDPATTERN/REPLACEPATTERN/g; However, I cannot figure out how to make the substitution occur over the contents of a file. The following... (3 Replies)
Discussion started by: LessNux
3 Replies

7. UNIX for Dummies Questions & Answers

Using "mailx" command to read "to" and "cc" email addreses from input file

How to use "mailx" command to do e-mail reading the input file containing email address, where column 1 has name and column 2 containing “To” e-mail address and column 3 contains “cc” e-mail address to include with same email. Sample input file, email.txt Below is an sample code where... (2 Replies)
Discussion started by: asjaiswal
2 Replies

8. Shell Programming and Scripting

Bash script - Print an ascii file using specific font "Latin Modern Mono 12" "regular" "9"

Hello. System : opensuse leap 42.3 I have a bash script that build a text file. I would like the last command doing : print_cmd -o page-left=43 -o page-right=22 -o page-top=28 -o page-bottom=43 -o font=LatinModernMono12:regular:9 some_file.txt where : print_cmd ::= some printing... (1 Reply)
Discussion started by: jcdole
1 Replies

9. AIX

Apache 2.4 directory cannot display "Last modified" "Size" "Description"

Hi 2 all, i have had AIX 7.2 :/# /usr/IBMAHS/bin/apachectl -v Server version: Apache/2.4.12 (Unix) Server built: May 25 2015 04:58:27 :/#:/# /usr/IBMAHS/bin/apachectl -M Loaded Modules: core_module (static) so_module (static) http_module (static) mpm_worker_module (static) ... (3 Replies)
Discussion started by: penchev
3 Replies
time(1) 						      General Commands Manual							   time(1)

Name
       time - time a command

Syntax
       time command
       /bin/time command

Description
       The  command  lets  the specified command execute and then outputs the amount of elapsed real time, the time spent in the operating system,
       and the time spent in execution of the command.	Times are reported in seconds and are written to standard error.

       If you are using any shell except the C shell, you can give the command as shown on the first line of the Syntax section.  If you are using
       the  C shell, you must use the command's full pathname as shown on the second line of the Syntax section.  If you do not use the full path-
       name, will execute its own built-in command that supplies additional information and uses a different output format.

       The command can be used to cause a command to be timed no matter how much CPU time it takes.  For example:
       % /bin/time cp /etc/rc /usr/bill/rc
	       0.1 real 	0.0 user	 0.0 sys
       % /bin/time nroff sample1 > sample1.nroff
	       3.6 real 	2.4 user	 1.2 sys
       This example indicates that the command used negligible amounts of user and system time and had an elapsed time of 1/10 second (0.1).   The
       command used 2.4 seconds of user time and 1.2 seconds of system time, and required 3.6 seconds of elapsed time.

Restrictions
       Times are measured to an accuracy of 1/10 second.  Thus, the sum of the user and system times can be larger than the elapsed time.

See Also
       csh(1)

																	   time(1)
All times are GMT -4. The time now is 09:43 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy