I am using Automator on my Mac to set up a service that passes a selected folder to a bash shell script as arguments.
In the script I do:
for f in "$#"; do
printf "%q\n" "$f" | pbcopy
done
if I then do:
echo `pbpaste`
I get the path to my selected folder with spaces escaped (\). I then wanted to use this path to cd into that directory and do a bunch of other stuff (creating a blank directory structure). I hoped I could just do:
cd `pbpaste`
but this doesn't work.
If I type the path manually the cd works so I assume the is some issue with data types or returns or something??
I'll admit I don't really know what this script actually doing and may be going about this all wrong but but if anyone can explain what's going on here and how to get it working it that would be great but even better would be a pointer to a really good resource for a complete beginner to start learning about shell scripting.
I really like the idea of getting into this a bit more but all the resources I have found are either total basics (cd, ls, pwd etc) or really high level and assume a bunch of previous knowledge.
What I'd really like is a full language reference with some actual examples like you find for the languages I am more used to (HTML/CSS/JS/AS3), if such a thing exists.
Cheers for any help :)
I'm agree with #chepner's answer, but for google's results sake, to cd using pbpaste you simply do:
cd $(pbpaste)
When you use the %q format, you are adding literal backslashes to the string, which the shell does not process as escape characters when you use it with cd.
The clipboard is useful for interprocess communication; inside a single script, it's easier to just use variables to hold information temporarily. f already has the path name in it, so just use it:
cd "$f"
Notice I've quoted the expansion of f, so that any spaces in the path name are passed as part of the single argument to cd.
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
Is there a way to preprocess a line entered into bash in interactive mode before it is processed by bash?
I'd like to introduce some custom shorthand syntax to deal with long paths. For example, instead of writing 'cd /one/two/three/four/five', I'd like to be able to write something like 'cd /.../five', and then my preprocessing script would replace this by the former command (if a unique directory 'five' exists somewhere below /).
I found http://glyf.livejournal.com/63106.html which describes how to execute a hook function before a command is executed. However, the approach does not allow to alter the command to be executed.
There's no good way of doing this generally for all commands.
However, you can do it for specific commands by overriding them with a function. For your cd case, you can stick something like this in your .bashrc:
cd() {
path="$1"
[[ $path == "/.../five" ]] && path="/one/two/three/four/five"
builtin cd "$path"
}
In bash 4 or later, you can use the globstar option.
shopt -s globstar
cd /**/five
assuming that five is a unique directory.
The short answer is not directly. As you have found, the PROMPT_COMMAND environment variable allows you to issue a command before the prompt is displayed, which can allow for some very creative uses, e.g. Unlimited BASH History, but nothing that would allow you to parse and replace input directly.
What you are wanting to do can be accomplished using functions and alias within your .bashrc. One approach would be to use either findutils-locate or simply a find command to search directories below the present working directory for the last component in the ellipsed path, and then provide the full path in return. However, even with the indexing, locate would take a bit of time, and depending on the depth, find itself may be to slow for generically doing this for all possible directories. If however, you had a list of specific directories you would like to implement something like this for, then the solution would be workable and relatively easy.
To provide any type of prototype or further detail, we would need to know more about how you intent to use the path information, and whether multiple paths could be provided in a single command.
Another issue arises if the directory five is non-unique...
This is one of my homework exercise.
Write a shell program, which will take a directory as an argument.
The script should then print all the regular files in the directory and all
the recursive directories, with the following information n the given order for
each of the files
File name (full name from the specified directory) file size owner
In case the directory argument is not given, the script should assume the
directory to be the current working directory
I am confused about how to approach this problem. For the listing of files part, I tried ls -R | awk ... but i was not able to do it because I was not able to find a suitable field seperator for awk.
I know its unfair to ask for a solution, but please can you guys give me a hint as how to proceed with the problem? Thanks in advance.
You really don't want to use ls and awk for this. Instead you want to check the documentation for find to figure out what string to put in the following script:
find ${1:-.} -type f -printf "format-string-to-be-determined-by-reader\n"
The problem is that parsing the output of ls is complicated at best and dangerous at worst.
What you'll want to do is use find to produce the list of files and a small shell script to produce the output you want. While there are many possible methods to accomplish this I would use the following general form
while read -r file ; do
# retrieve information about $file
# print that information on one line
done < <(find ...)
With a suitable find command to select the files. To retrieve the metadata about the files I would use stat inside the loop, probably multiple times.
I hope that's enough of a hint, but If you want a complete answer I can provide.
awk is fine.. use " +" as separator.
Bah. Where's the challenge in using ls or find? May as well write a one-liner in perl to do all the work, and then just call the one-liner from a script. ;)
You can do your recursive directory traversal in the shell natively, and use stat to get the size and owner. Basically, you write a function to list the directory (for element in *), and have the function change to the directory and call itself if [[ -d $element ]] is true. Something like
do_print "$elem"
if [[ -d "$elem" ]]
then
cd "$elem"
process_dir
cd ..
fi
or something akin to that.
Yeah, you'll have a zillion system calls to stat, but IMHO that's probably preferable to machine-parsing the output of a program whose output is intended to be human-readable. In this case, where performance is not an issue, it's worth it.
For bonus super happy fun times, change the value of IFS to a value which won't appear in a filename so the shell globbing won't get confused by files containing whitespace in its name. I'd suggest either a newline or a slash.
Or take the easy way out and just use find with printf. :)
I'm trying to run a script which uses my $HOME variable to set things up (it's gitolite, by the way).
However, it's failing because I'm on a system where the home directory path has spaces in it.
I want to hack the gitolite bash script at a single point so $HOME turns into something it can work with -- it gets used several times in the script and beyond, and in some places is concatenated to form subfolders, so wrapping it in "" won't work.
So to clean it up I need to say something like:
$HOME=(magic here)$HOME
(This is of course assuming that the perl scripts that come later don't also read the $HOME variable direct and also need fixing...)
Use quotes everywhere.
HOME="/Users/Foo Bar"
WORKDIR="$HOME"/Work
PLAYDIR="$HOME"/Games
MARATHONDIR="$PLAYDIR"/Marathon
Try this:
export HOME=`echo $HOME | sed -e "s/ /\\ /g"`
Hope that works for you!
I am calling a script as below
directory path : /user/local/script/print_path.sh
var_path=`pwd`
echo $var_path
The above script is calling as below
directory path : /user/local/callPscript/call.sh
`/user/local/script/print_path.sh`
I want the out put as below :
/user/local/script/
But it gives the output :
/user/local/callPscript/
i.e. the pocation of the script is called. How can I make it to the scripts home directory path?
After some weeks of Bash programming, this has emerged as the standard solution:
directory=$(dirname -- $(readlink -fn -- "$0"))
$0 is the relative path to the script, readlink -f resolves that into an absolute path, and dirname strips the script filename from the end of the path.
A safer variant based on the completely safe find:
directoryx="$(dirname -- $(readlink -fn -- "$0"; echo x))"
directory="${directoryx%x}"
This should be safe with any filename - $() structures remove newlines at the end of the string, which is the reason for the x at the end.
May be this can help you.
var_path=$PWD
echo $var_path
Try this one, it should come close to what you want:
var_path=`dirname "$0"`
Please see BashFAQ/028.
This topic comes up frequently. This answer covers not only the expression used above ("configuration files"), but also several variant situations. If you've been directed here, please read this entire answer before dismissing it.
This is a complex question because there's no single right answer to it. Even worse: it's not possible to find the location reliably in 100% of all cases. All ways of finding a script's location depend on the name of the script, as seen in the predefined variable $0. But providing the script name in $0 is only a (very common) convention, not a requirement.
. . .
Generally, storing data files in the same directory as their programs is a bad practise. The Unix file system layout assumes that files in one place (e.g. /bin) are executable programs, while files in another place (e.g. /etc) are data files.
Read the complete page for lots more good information.