I've got a script on my computer named test.py. What I've been doing so far to run the program is type python test.py into the terminal.
Is there a command on Unix operating systems that doesn't require the user to specify the program he/she uses to run the script but that will instead run the script using whichever program the shebang line is pointing to?
For example, I'm looking for a command that would let me type some_command test.txtinto the terminal, and if the first line of test.txt is #!/usr/bin/python, the script would be interpreted as a python script, but if the first line is #!/path/to/javascript/interpreter, the the script would be interpreted as javascript.
This is the default behavior of the terminal (or just executing a file in general) all you have to do is make the script executable with
chmod u+x test.txt
Then (assuming text.txt is in your current directory) every time you type
./text.txt
It will look at the sh-bang line and use the program there to run text.txt.
If you really want to duplicate built-in functionality, try this.
#!/bin/sh
x=$1
shift
p=$(sed -n 's/^#!//p;q' "$x" | grep .) && exec $p "$#"
exec "$x" "$#"
echo "$0: $x: No can do" >&2
Maybe call it start to remind you of the similarly useful Windows command.
Related
I am using this command to copy file from remote server to local machine:
scp -r app:/home/dolphin/model* .
In bash it works fine.In zsh it throw this error:zsh: no matches found: app:/home/dolphin/model*.I am searching from Google and understand the bash and zsh have different rule of glob.Here is my question:
what is the execute step detail of this command?
anyone could tell me the shell how to execute the command,the first step is echo the path of this command?
I could use -v(verbose) to see the scp execute process.
I am unfamiliar with Zsh, but as far as I can say, Bash will pass the original string to the program as an argument if nothing is globbed, while it appears that Zsh complains in this case.
To ensure the "unglobbed" string is passed as an argument to scp(1), you can escape the asterisk:
scp -r app:/home/dolphin/model\* .
^^
I am hoping someone can help me figure out what setting I might need to overwrite. I am working on a Unix terminal server, running a Linux Xterm linux shell. Everytime I use a command like grep "blah" 2> /dev/null at the shell prompt, the command is run as grep "blah" 2 > /dev/null and needless to say the redirection fails.
xterm version is X.Org 6.8.99.903(238)
I can not update or install anything, this is a locked down production server.
Thanks for any help and illumination on the topic, it is making my grep useless at high directory levels with recursion.
That's Bourne shell syntax, and it doesn't work in c-shell.
The best you can do is
( command >stdout_file ) >&stderr_file
Where you get stdout to one file, and stderr to another. Redirecting just stderr is not possible.
In a comment, you say "A minor note, this is csh". That's not a minor note, that's the cause of the problem. xterm is just a terminal emulator, not a shell; all it does is set up a window that provides textual input and output. csh (or bash, or ...) is the shell, the program that interprets the commands you type.
csh has different syntax for redirection, and doesn't let you redirect just stderr. command > file redirects stdout; command >& file redirects both stdout and stderr.
You say the system doesn't have bash, but it does have ksh. I suggest just using ksh; it will be a lot more familiar to you. Both bash and ksh are derived from the old Bourne shell.
All (?) Unix-like systems will have a Bourne-like shell installed as /bin/sh. Even if you're using csh (or tcsh?) as your interactive shell, you can still invoke sh, even in a one-liner. For example:
sh -c 'command 2>/dev/null'
will invoke sh, which in turn will invoke command and redirect just its stderr to /dev/null.
The purpose of an interactive shell is (mostly) to let you use other commands that are available on the system. sh, or any shell, can be used as just another command.
I would like to my terminal current directory follows my VIM one.
Example:
In TERMINAL:
> pwd
=> /Users/rege
> vim
Then in VIM
:cd /Users/rege/project
<Ctrl-z>(for suspend)
In terminal
> pwd
=> /Users/rege/project
I`m using MacOS, zsh, tmux.
I need this because when Im trying to use tags in VIM, tags are check in project from my terminal directory not vim one.
So I need to change terminal current directory always when I change VIM current directory.
What kind of command do you issue in your shell after you suspend Vim? Isn't Vim's :!command enough?
With set autochdir, Vim's current directory follows you as you jump from file to file. With this setting, a simple :!ctags -R . will always create a tags file in the directory of the current file.
Another useful setting is set tags=./tags,tags;$HOME which tells Vim to look for a tags file in the directory of the current file, then in the "current directory" and up and up until it reaches your ~/. You might modify the endpoint to suit your needs. This allows you to use a tags at the root of your project while editing any file belonging to the project.
So, basically, you can go a long way without leaving Vim at all.
If you really need to go back to the shell to issue your commands, :shell (or :sh) launchs a new shell with Vim's current directory. When you are done, you only have to $ exit to go back to Vim:
$ pwd
/home/romainl
$ vim
:cd Projects
:sh
$ pwd
/home/romainl/Projects
$ exit
In bash or zsh and on Unix you can do this: current working directory of the process is represented in /proc/{PID}/cwd as a symlink to a real directory. Speaking about zsh the following code will do the job:
function precmd()
{
emulate -L zsh
(( $#jobstates == 1 )) || return
local -i PID=${${${(s.:.)${(v)jobstates[1]}}[3]}%\=*}
cd $(readlink /proc/$PID/cwd)
}
. Note: with this code you won’t be able to pernamently switch directories in terminal anymore, only in vim or for duration of one command (using cd other-dir && some command).
Note 2: I have no idea how to express this in bash. The straightforward way is to get PIDs of all children of the shell (using ps --ppid $$ -o CMD), filter out the ps process (it will be shown as a child as well), check that there is only one other child and use its PID like in the last line above. But I am pretty sure there is a better way using some shell builtins like I did with zsh’s $jobstates associative array. I also don’t remember what is the analogue of precmd in bash.
Another idea would be making vim save its current directory into some file when you do <C-z> and make shell read this in precmd:
" In .vimrc:
function s:CtrlZ()
call writefile([fnamemodify('.', ':p')], $CWDFILE, 'b')
return "\<C-z>"
endfunction
nnoremap <expr> <C-z> <SID>CtrlZ()
# In .zshrc
function vim()
{
local -x CWDFILE=~/.workdirs/$$
test -d $CWDFILE:h || mkdir $CWDFILE:h
vim $#
}
function precmd()
{
local CWDFILE=~/.workdirs/$$
test -e $CWDFILE && cd "$(cat $CWDFILE)"
}
. It should be easier to port above code to bash.
you can open a new terminal like this
:!xterm -e bash -c "cd %:p:h;bash" &
actually I write this in my .vimrc
nmap <F3> :!xterm -e bash -c "cd %:p:h;bash" &<CR> | :redraw!
For bash users coming by:
Vim: Save pwd at <c-z> (with map and getpwd()).
Bash: Before prompt command, goto directory indicated by vim with PROMPT_COMMAND.
.bashrc
PROMPT_COMMAND='read -r line 2>/dev/null </tmp/cd_vim'\
'&& > /tmp/cd_vim && cd ${line##\r};'$PROMPT_COMMAND
vimrc
function! s:CtrlZ() call writefile([getcwd(),''], '/tmp/cd_vim', 'b')
return "\<C-z>"
endfunction
nnoremap <expr> <C-z> <SID>CtrlZ()
This is ZyX answer edited for bash https://stackoverflow.com/a/12241861/2544873
i'm running a script from ASP.NET/C# using SharpSsh. I realize when the script runs and i do a ps -ef grep from unix, i see the same script running twice, one in csh -c, and the other with ksh. The script has shebang ksh, so i'm not sure why a copy of csh is also running. Also if i run the same script directly from unix, only one copy runs with ksh. There's no other shell running from within the script.
Most Unix/Linux now have a command or option that will show process trees, with indented list like, look for -t or -T options to ps OR ptree OR ???
USER PID PPID START TT TIME CMD
daemon 1 1 11-03-06 ? 0 init
myusr 221568 1 11-03-07 tty10 1.00s \_ -ksh
myusr 350976 221568 07:52:11 tty10 0 | \_ ps -efT
I bet you'll see that the csh is the user login shell that includes your script as an argument ( you may have to use different options to ps to see the full command-line of the csh process) AND as a sub process you'll see ksh executing your script, and further sub-processes under ksh for any external commands that the script is calling.
I hope this helps.
P.S. as you appear to be a new user, if you get an answer that helps you please remember to mark it as accepted, or give it a + (or -) as a useful answer.
I have a script that looks like this
#!/bin/bash
function something() {
echo "hello world!!"
}
something | tee logfile
I have set the execute permission on this file and when I try running the file like this
$./script.sh
it runs perfectly fine, but when I run it on the command line like this
$sh script.sh
It throws up an error. Why does this happen and what are the ways in which I can fix this.
Running it as ./script.sh will make the kernel read the first line (the shebang), and then invoke bash to interpret the script. Running it as sh script.sh uses whatever shell your system defaults sh to (on Ubuntu this is Dash, which is sh-compatible, but doesn't support some of the extra features of Bash).
You can fix it by invoking it as bash script.sh, or if it's your machine you can change /bin/sh to be bash and not whatever it is currently (usually just by symlinking it - rm /bin/sh && ln -s /bin/bash /bin/sh). Or you can just use ./script.sh instead if that's already working ;)
If your shell is indeed dash and you want to modify the script to be compatible, https://wiki.ubuntu.com/DashAsBinSh has a helpful guide to the differences. In your sample it looks like you'd just have to remove the function keyword.
if your script is at your present working directory and you issue ./script.sh, the kernel will read the shebang (first line) and execute the shell interpreter that is defined. you can also call your script.sh by specifying the path of the interpreter eg
/bin/bash myscript.sh
/bin/sh myscript.sh
/bin/ksh myscript.sh etc
By the way, you can also put your shebang like this (if you don't want to specify full path)
#!/usr/bin/env sh
sh script.sh forces the script to be executed within the sh - shell.
while simply starting it from command line uses the shell-environemnt you're in.
Please post the error message for further answers.
Random though on what the error may be:
path specified in first line /bin/bash is wrong -- maybe bash is not installed?