We're not ignoring you if we haven't answered the instant you want an answer. You don't have to bump threads. In fact you shouldn't, it's against the rules you read and agreed to when you registered.
I don't think you've got that quite right. Without complex structures like brackets or loops, a command after a pipe needs no subshell. The shell just creates a new process, arranges the files how you wanted, and replaces the new process with the requested command.
A subshell does have to stick around to manage situations like you illustrated:
It has to stay resident in order to wait for command2 to finish before starting command3.
A subshell also exists in a situation like this:
The subshell has to stay resident to process code after the pipe inside the loop.
These subshells have side-effects. Try this:
It will output "hello", since variables changed inside the subshell aren't changed in its parent.
can we use pipes to redirect the output of any command to grep .....
like i wanted to write this script about checking the online status of a certain user so ...can i send the output of who to grep directly using pipes...
one way was this :
who > temp
grep $uname temp
i was wondering if... (4 Replies)
Hi All
Here i have a piece of code,
set filename "./GopiRun.sh"
#I need to wait here until the GopiRun.sh is completed how do i achive this
exit. (1 Reply)
Hi Guys,
Just a question about subprocesses.. Lately one of our servers has started to throw out the following error:
SYSTEM ERROR: Too many subprocesses, cannot fork. Errno=12
We've already increased the threshold twice. Its now up to 8000 and the swap space has also been increased. We... (6 Replies)
Hi,
I am trying to run a shell script using subprocess in python.
I can run simple script with arguments using subprocess.But I am not able to embed xterm in subrocess command.
#!/usr/bin/python
import subprocess
subprocess.call()
Above code gives me error.
Please help me in... (2 Replies)
Hi guys,
I'm learning python and perl and i was trying to run from python a perl script using the subprocess module.
I have an issue that i don't understand regarding this.
I run this code:
#!/usr/bin/python
import subprocess
p2 = subprocess.Popen(,stdout=subprocess.PIPE)
output2 =... (2 Replies)
After struggling with this for days now, I'm reaching out to the experts of all things linux for some help with this.
I'm trying to run the following working command (on command line) inside a python script using subprocess:
rsync -avzh --no-perms --delete --include="*sub*" --exclude='*'... (2 Replies)
So I have this basic script, see below
import subprocess
import shlex
command = "gcloud projects list"
subprocess.check_output(shlex.split(command))
subprocess.check_call(shlex.split(command))
The subprocess.check_call(shlex.split(command)) actually return what I expect. It returns... (6 Replies)
Discussion started by: scj2012
6 Replies
LEARN ABOUT SUNOS
echo
echo(1B) SunOS/BSD Compatibility Package Commands echo(1B)NAME
echo - echo arguments to standard output
SYNOPSIS
/usr/ucb/echo [-n] [argument]
DESCRIPTION
echo writes its arguments, separated by BLANKs and terminated by a NEWLINE, to the standard output.
echo is useful for producing diagnostics in command files and for sending known data into a pipe, and for displaying the contents of envi-
ronment variables.
For example, you can use echo to determine how many subdirectories below the root directory (/) is your current directory, as follows:
o echo your current-working-directory's full pathname
o pipe the output through tr to translate the path's embedded slash-characters into space-characters
o pipe that output through wc -w for a count of the names in your path.
example% /usr/bin/echo "echo $PWD | tr '/' ' ' | wc -w"
See tr(1) and wc(1) for their functionality.
The shells csh(1), ksh(1), and sh(1), each have an echo built-in command, which, by default, will have precedence, and will be invoked if
the user calls echo without a full pathname. /usr/ucb/echo and csh's echo() have an -n option, but do not understand back-slashed escape
characters. sh's echo(), ksh's echo(), and /usr/bin/echo, on the other hand, understand the black-slashed escape characters, and ksh's
echo() also understands a as the audible bell character; however, these commands do not have an -n option.
OPTIONS -n Do not add the NEWLINE to the output.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWscpu |
+-----------------------------+-----------------------------+
SEE ALSO csh(1), echo(1), ksh(1), sh(1), tr(1), wc(1), attributes(5)NOTES
The -n option is a transition aid for BSD applications, and may not be supported in future releases.
SunOS 5.10 3 Aug 1994 echo(1B)