On MSYS2 on my Windows machine, I have to switch to bash because tcsh is flaky and after an hour of messing around with completion scripts, .bashrc and .inputrc, I have almost got bash to behave in a way I am used to. However, there's one piece missing.
In tcsh, I could list the current directory on a single TAB press (i.e., a blank command). I am sure there's a way to do this in bash with the complete -E option, but I can find no examples.
Any help is appreciated!
Regards
This will do what you want:
complete -Ef
Now try <tab><tab>
I was able to get what I wanted with this:
_listall ()
{
COMPREPLY+=( $( ls ./))
}
complete -F _listall -E
Related
I am trying to run the next code on bash. It is suppose to work but it does not.
Can you help me to fix it? I am starting with programming.
The code is this:
for i in {1:5}
do
cd path-to-folder-number/"$i"0/
echo path-to-folder-number/"$i"0/
done
EXAMPLE
I want to iterate over folders which have numbers (10,20..50), and so it changes directory from "path-to-folder-number/10/" to "path-to-folder-number/20/" ..etc
I replace : with .. but it is not working yet. When the script is applied i get:
can't cd to path-to-folder-number/{1..5}0/
I think there are three problems here: you're using the wrong shell, the wrong syntax for a range, and if you solved those problems you may also have trouble with successive cds not doing what you want.
The shell problem is that you're running the script with sh instead of bash. On some systems sh is actually bash (but running in POSIX compatibility mode, with some advanced features turned off), but I think on your system it's a more basic shell that doesn't have any of the bash extensions.
The best way to control which shell a script runs with is to add a "shebang" line at the beginning that says what interpreter to run it with. For bash, that'd be either #!/bin/bash or #!/usr/bin/env bash. Then run the script by either placing it in a directory that's in your $PATH, or explicitly giving the path to the script (e.g. with ./scriptname if you're in the same directory it's in). Do not run it with sh scriptname, because that'll override the shebang and use the basic shell, and it won't work.
(BTW, the name "shebang" comes from the "#!" characters the line starts with -- the "#" character is sometimes called "sharp", and "!" is sometimes called "bang", so it's "sharp-bang", which gets abbreviated to "shebang".)
In bash, the correct syntax for a range in a brace expansion is {1..5}, not {1:5}. Note that brace expansions are a bash extension, which is why getting the right shell matters.
Finally, a problem you haven't actually run into yet, but may when you get the first two problems fixed: you cd to path-to-folder-number/10/, and then path-to-folder-number/20/, etc. You are not cding back to the original directory in between, so if the path-to-folder-number is relative (i.e. doesn't start with "/"), it's going to try to cd to path-to-folder-number/10/path-to-folder-number/20/path-to-folder-number/30/path-to-folder-number/40/path-to-folder-number/50/.
IMO using cd in scripts is generally a bad idea, because there are a number of things that can go wrong. It's easy to lose track of where the script is going to be at which point. If any cd fails for any reason, then the rest of the script will be running in the wrong place. And if you have any files specified by relative paths, those paths become invalid as soon as you cd someplace other than the original directory.
It's much less fragile to just use explicit paths to refer to file locations within the script. So, for example, instead of cd "path-to-folder-number/${i}0/"; ls, use ls "path-to-folder-number/${i}0/".
For up ranges the syntax is:
for i in {1..5}
do
cd path-to-folder-number/"$i"0/
echo $i
done
So replace the : with ..
To get exactly what you want you can use this:
for i in 10 {20..50}
do
echo $i
done
You can also use seq :
for i in $(seq 10 10 50); do
cd path-to-folder-number/$i/
echo path-to-folder-number/$i/
done
I am writing a bash script which uses here strings (<<<), please see example below. The script works fine and gives expected output, but the problem is that the (vim) editor syntax color is all messed up after the line where here string was used. Any clues why and also how I can fix it ?
As text:
# get all running screens
scrcmd=$(ps auxw|grep -i screen|grep -v grep|awk '{print $15}')
allscr=()
while read -r line; do
allscr+=("$line")
done <<< $scrcmd
echo "got screens, now do something else"
The bash (really sh) highlight mode in Vim is multipurpose; it tries to cover POSIX sh, bash, and ksh. You have to tell it you specifically want bash.
:let b:is_bash=1
:set ft=sh
It should highlight properly after that.
If you only ever care about bash, you could just make this your default in .vimrc:
let g:is_bash=1
EDIT: As pointed out by Charles Duffy in comments, if you use a #! line, e.g.
#!/bin/bash
#!/usr/bin/env bash
Then vim should do the right thing on its own. That is probably easier, unless you have some reason you prefer not use #! lines.
(Even though that's likely easier, I am leaving my answer here because in this case you do not have a #! line, and that is not uncommon, especially in library code or files expected to be sourced, not executed.)
I have a script which takes a UUID as the argument. When I run it manually I can access it using custom tab completion I have written. Is there a way of accessing this completion in a shell script?
~/myscript stop 0011<tab>
It will complete to:
~/myscript stop 0011-1111-1111-1111
Edit:
For example:
#!/bin/bash
echo "~/myscript stop \t" | bash -i
The bash completion is already written. I'm currently executing it in another interactive shell, is there a way of executing this is the same shell?
I'm not sure why you can't just put the full UUID into your script. But I expect that you can do what you want to do using the bash compgen builtin.
I haven't played with compgen much and I've never used custom tab completion, so I can't give you detailed instructions, but using compgen to generate a list of possible filename completions is easy enough.
Eg, in my home directory,
compgen -f .ba
prints
.bash_history
.bashrc.dpkg-old
.bashrc
.bash_logout
.bashrc~
I'm trying to get last executed command from command line from a script to be saved for a later reference:
Example:
# echo "Hello World!!!"
> Hello World!!!
# my_script.sh
> echo "Hello World!!!"
and the content of the script would be :
#!/usr/bin/ksh
fc -nl -1 | sed -n 1p
Now as you notices using here ksh and fc is a built in command which if understood correctly should be implemented by any POSIX compatible shells. [I understand that this feature is interactive and that calling same fc again will give different result but this is not the concern do discuss about]
Above works so far so good only if my_script.sh is being called from the shell which is as well ksh, or if calling from bash and changing 1st line of script as #!/bin/bash then it works too and it doesn't if shells are different.
I would like to know if there is any good way to achieve above without being constrained by the shell your script is called from. I understand that fc is a built in command and it works per shell thus most probably my approach is not good at all from what I want to achieve. Any better suggestions?
I actually attempted this, but it cannot be done between different shells consistently.
While
fc -l`,
is the POSIX standard command for showing $SHELL history, implementation details may be different.
At least bash and ksh93 both will report the last command with
fc -n -l -1 -1
However, POSIX does not guarantee that shell history will be carried over to a new instance of the shell, as this requires the presence of a $HISTFILE. If none is
present, the shell may default to $HOME/.sh_history.
However, this history file or Command History List is not portable between different shells.
The POSIX Shell description of the
Command History List says:
When the sh utility is being used interactively, it shall maintain a list of commands
previously entered from the terminal in the file named by the HISTFILE environment
variable. The type, size, and internal format of this file are unspecified.
Emphasis mine
What this means is that for your script needs to know which shell wrote that history.
I tried to use $SHELL -c 'fc -nl -1 -1', but this did not appear to work when $SHELL refers to bash. Calling ksh -c ... from bash actually worked.
The only way I could get this to work is by creating a function.
last_command() { (fc -n -l -1 -1); }
In both ksh and bash, this will give the expected result. Variations of this function can be used to write the result elsewhere. However, it will break whenever it's called
from a different process than the current.
The best you can do is to create these functions and source them into your
interactive shell.
fc is designed to be used interactively. I tested your example on cygwin/bash and the result was different. Even with bash everywhere the fc command didn't work in my case.
I think fc displays the last command of the current shell (here I don't speak about the shell interpretor, but shell as the "process box". So the question is more why it works for you.
I don't think there is a clean way to achieve what you want because (maybe I miss something) you want two different process (bash and your magic command [my_script.sh]) and by default OS ensure isolation between them.
You can rely on what you observe (not portable, depends on the shell interpretor etc.)
You cannot rely on BASH historic because it's in-memory (the file is updated only on exit).
You can use an alias or a function (edited: #Charles Duffy is right). In this case you won't be able to use your "magic command" from another terminal, but for an interactive use it does the job.
Edited:
Or you can provide two commands: one to save and another to look for. In this case you manage your own historic but you have to save explicitly each command that is painful...
So I look for a hook. And I found this other thread : https://superuser.com/questions/175799/does-bash-have-a-hook-that-is-run-before-executing-a-command
# At the beginning of the Shell (.bashrc for example)
save(){ history 1 >>"$HOME"/myHistory ; }
trap 'save' DEBUG
# An example of use
rm -f "$HOME"/myHistory
echo "1 2 3"
cat "$HOME"/myHistory
14 echo "1 2 3"
15 cat "$HOME"/myHistory
But I observe it slows down the interpretor...
Little convoluted, but I was able to use this command to get the most recent command in zsh, bash, ksh, and tcsh on Linux:
history | tail -2 | head -1 | sed -r 's/^[ \t]*[0-9]*[ \t]+([^ \t].*$)/\1/'
Caveats: this uses GNU sed, so you'll need to install that if you're using BSD, OS X, etc; and also, tcsh will display the time of the command before the command itself. Regular csh doesn't seem to having a functioning history command when I tried it.
Here's my situation:
I have multiple versions of a script in source code control where the name differs by a path name component (ex: scc/project/1.0/script and scc/project/1.1/script). In another directory, there is a symlink to one of these scripts. The symlink name is not related to the script name, and in some cases may change periodically. That symlink, in turn, is sourced by bash using the '.' command.
What I need to know: how do I determine the directory of the referenced script, on a 10 year-old system with Bash 2 and Perl 5.5? For various reasons, the system must be used, and it cannot be upgraded.
In Bash 3 or above, I use this:
dir=`perl -MCwd=realpath -MFile::Basename 'print dirname(realpath($ARGV[0]))' ${BASH_SOURCE[0]} $0`
Apologies for the Perl one-liner - this was originally a pure-Perl project with a very small amount of shell script glue.
I've been able to work around the fact that the ancient Perl I am using doesn't export "realpath" from Cwd, but unfortunately, Bash 2.03.01 doesn't provide BASH_SOURCE, or anything like it that I've been able to find. As a workaround, I'm providing the path information in a text file that I change manually when I switch branches, but I'd really like to make this figure out which branch I'm using on its own.
Update:
I apologize - apparently, the question as asked is not clear. I don't know in every case what the name of the symlink will be - that's what I'm trying to find out at run time. The script is occasionally executed via the symlink directly, but most often the link is the argument to a "." command running in another script.
Also, $0 is not set appropriately when the script is sourced via ".", which is the entire problem I'm trying to solve. I apologize for bluntness, but no solution that depends entirely upon $0 being set is correct. In the Perl one-liner, I use both BASH_SOURCE and $0 (BASH_SOURCE is only set when the script is sourced via ".", so the one-liner only uses $0 when it's not sourced).
Try using $0 instead of ${BASH_SOURCE[0]}. (No promises; I don't have a bash 2 around.)
$0 has the name of the program/script you are executing.
Is stat ok? something like
stat -c %N $file
bash's cd and pwd builtins have a -P option to resolve symlinks, so:
dir=$(cd -P -- "$(dirname -- "$0")" && pwd -P)
works with bash 2.03
I managed to get information about the porcess sourcing my script using this command:
ps -ef | grep $$
This is not perfect but tells your which is the to process invoking your script. It migth be possible with some formating to determine the exact source.