I have example file: test_file
//--- Test File--
**RUN_THIS
RUN_THIS00
RUN_THIS01
DONT_RUN00
DONT_RUN00
RUN_THIS02**
where RUN_THIS* & DONT_RUN* are commands.
I would like to run only RUN_THIS commands from test_file without editing the file.
I am looking for option like
cat test_file | grep RUN_THIS | xargs {Some option to be provided to run run_this}
I cannot start new shell
Something like this perhaps?
for cmd in $(grep RUN_THIS < test_file); do
$cmd --some-option-to-be-provided-to-run-this
done
That should work okay as long as there are no spaces in the commands in test_file.
eval `grep RUN_THIS test_file`
Note also the avoidance of a Useless Use of Cat.
Actually, you may have to add a semicolon to the end of each command in test_file, or change the grep to something which adds the necessary semicolons.
eval `awk '/RUN_THIS/ { print; print ";" }'`
I'm not sure I understand the requirement to not start a new shell. Under the hood, the backticks run a subshell, so this might violate that requirement (but then ultimately every external command starts a new process, which starts out as a fork of the current shell process when you run a shell script). If you are scared of security implications, you should not be using a shell script in the first place, anyhow.
To run new shells you need to incorparate "ksh" in your command.
In its simplest form
RUN_THIS00='ls'
echo $RUN_THIS00 | ksh
Related
I'm using AS perl on win7.
print `cd \\\\ `; # does nothing, says nothing
Same with qx()
print `dir \\\\ `; # correctly prints the root directory
other commands also seem to work fine.
cd works fine from the command line of a batch file.
Has anyone else seen this? Is there a workaround?
You may be looking for chdir. Using a shell command in backticks is not going to have a lasting effect. When you run a backtick command, you spawn a new shell, execute the command, and return the standard output to Perl. Then the shell exits and any and all changes to it is lost.
perldoc -q changed
I {changed directory, modified my environment} in a perl script. How come the change disappeared when I exited the script? How do I get my changes to be visible?
In the strictest sense, it can't be done--the script executes as a different process from the shell it was started from. Changes to a process are not reflected in its parent--only in any children created after the change.
I need to be able to run a script from within a script but first I need to ssh as a different user and then change my group.
I am currently doing the following inside my perl script:
`ssh <user>#<host> ; newgrp <group> ; /script/to/run.pl`
When running this command form the command line it doesn't seam to switch groups. I assume this is because it's changing to a new shell.
How do I get around this and get it to work?
Also, please note, I do not have sudo/root privelages.
The first semicolon is interpreted by the local shell. So the three commands are run on the same host. I think you want this
ssh <user>\#<host> "newgrp <grp>; /bin/run.pl"
salva, in his reply, answered my question:
sg $group -c '$cmd'
The reason the following command:
newgrp <int>
doesn't work is because it creates a new shell. At least that is my best guess. the "sg" command gets around this.
I have found the following to work (with ksh on hpux) :
ssh user#host "echo 'date;pwd;echo bozo;id' | newgrp nerds;"
which basically executes the commands as user:nerds :
I think OP wants to construct a string to execute from Perl, notice the backticks. Not sure but OP might have to use:
$s='ssh <user>#<host> ; newgrp <group> ; /script/to/run.pl'; # Normal single quotes not backticks
exec($s);
OP, there are different ways to execute shell functions from a Perl script. You used backticks. There is also exec($s) and system($s).
In python, I can run a script and enter interactive mode in the context of that script. This lets me mess with global variables and what not to examine program state.
$ python -i hello.py
Can I do this with Coffeescript? I've tried the following:
$ coffee -i hello.coffee
doesn't load hello.coffee. It's equivalent to coffee -i
$ cat hello.coffee | coffee -i
runs the script line by line in REPL but ends REPL after the EOF.
I've recently started a project to create an advanced interactive shell for Node and associated languages like CoffeeScript. One of the features is loading a file or string in the context of the interpreter at startup which takes into account the loaded language.
http://danielgtaylor.github.com/nesh/
Example:
# Load a string
nesh -c -e 'hello = (name) -> "Hello, #{name}"'
# Load a file
nesh -c -e hello.coffee
Then in the interpreter you can access the hello function. Also a good idea to create an alias in bash:
alias cs='nesh -c'
cat foo.coffee - | coffee -i
tells cat to first output your code and then output stdin, which gives you what you're looking for I think.
I am confronted with this problem as well. The one provide by #int3 doesn't solve this problem, for CoffeeScript is one indentation based language. stdin will pass the code line by line, but the repl is not smart enough to realize this. Since you post this question, I suggest you create one issue (feature request) on CoffeeScript
I am looking for a nice way to get the following done:
So I have a script that I need to run in Python in Unix by calling from a Perl script that was, in turn, called from my Excel VBA macro in Windows using Plink. The Python script, due to dependency issues, has to run in either csh or bash, and I will need to use export/setenv to add a few libraries before running the script. However by default, perl runs in sh shell and as such, there is no way I can add in all the dependencies and have the Python script to run.
So, I am just wondering if there is EITHER: 1. a way for me to add dependencies to sh shell in the perl script, OR 2. force my perl script to run in csh (preferred, since for some reason .bashrc for the account runs into permission issues).
Thanks a lot!
How about "3. Set the appropriate environment variable in the Perl or Python scripts"?
$ENV{'PATH'} = ...
...
os.environ['PATH'] = os.pathsep.join(newpaths + os.environ['PATH'].split(os.pathsep))
(dunno how to get the path separator in Perl, sorz)
To force the shell to csh, try the following in Perl :
`/bin/csh -c "command_name"`;
Edit:
You can use ENV variable, like this. Try that :
$s = `/bin/bash -c 'VAR_FOO=753; echo \$VAR_FOO'`;
print $s;
I ended up just change the .cshrc script, apparently the addition to PATH, for some reason, did not work for me. After that, everything runs smoothly by putting all into one line
so basically it looks something like this
/path/to/.cshrc && /python/path/to/python
Hope that helps!
In Unix, I have a process that I want to run using nohup. However this process will at some point wait at a prompt where I have to enter yes or no for it to continue. So far, in Unix I have been doing the following
nohup myprocess <<EOF
y
EOF
So I start the process 'myprocess' using nohup and pipe in a file with 'y' then close the file. The lines above are effectively three seperate commands - i.e. I hit enter on the first line in UNIX, then I get a prompt where I enter 'y' and then press enter to then finally type 'EOF' and hit return again.
I want to know execute this in Perl but I am not sure how I can execute this command as it is over three lines. I don't know if the following will work....
my $startprocess = `nohup myprocess <<EOF &
y
EOF
`
Please help - thank you!
I think your proposal will work as is. If not, try replacing the redirect with a pipe:
my $startprocess = `(echo "y" | nohup myprocess) &`;
Also, depending on WHY you are doing a nohup, please look at the following pure Perl daemonizing approach using Proc::Daemon : How can I run a Perl script as a system daemon in linux?
Expect for interactive programs can be used as well.