/prog/ - Programming

I was working on a script to copy all my Ebooks and convert them to my preferable extension.

Now I crave a script that removes the last character from the filenames in a directory.

>>2487

Assuming you're on a relatively mainstream Gahnoo+Leenooks distro:

find . -type f -exec rename 's/.$//' '{}' +

Or, alternatively, if there are no subdirectories:

rename 's/.$//' *

For future reference, rename can change file extensions too:

rename 's/\.old/.new/' *.old

>>2488

Bless you for the effort, but they don't seem to work.

"SpecialVariables

"

Is one of the file names, deleting all nonalphanumeric whitespaces might do the trick.

>>2489

>newlines at the end of the files

In that case, try this (just run it in the offending directory):

#!/usr/bin/env python2.7

import os
import sys

for file in os.listdir("."):
    try:
        # Skip dot files
        if file[:1] == '.':
            continue

        # Skip things that are not files
        with open(file):
            os.rename(file, file[:-1])

    except IOError as err:
        # Whine and complain
        sys.stderr.write("%s\n" % str(err))

    except OSError:
        # Whine and complain louder
        sys.stderr.write("failed to rename file: `%s'\n" % file)

>>2490

Thank you very much!

check_ses()
{
	sudo -u ${USER} tmux has-session -t $TMUX_CONSOLE
}

How do I get this to return the results instead of printing it to stdout?

>>2514

>How do I get this to return the results instead of printing it to stdout?

You can't.

You can store the output in a variable though:

OUTPUT=$(check_ses)

if [ "$?" -eq 0 ]; then
    # Command was successful
else
    # Command failed
fi

What this does is causes the shell to fork - the child shell executes the shell function,

then the parent reads the output of the child shell and stores it in a variable, OUTPUT.

I'm not even trolling.

is there a difference and does it matter if i do

result=$(echo "$foo")

vs

result="$(echo $foo)"

?

>>2548

Double quotes tell the shell that everything in between is a single argument.

If you don't have double quotes, then the shell splits up the expanded variable.

For example, if "$foo" is "-n foo bar bazz", then this:

result=$(echo "$foo")

Would give you "-n foo bar bazz", while this:

result="$(echo $foo)"

Gives you "foo bar bazz".

>>2552

nice example, thanks.

and i suppose i can do

result="$(echo "$foo")"

because the quotes inside the brackets are evaluated separately from those around them?

>>2555

>because the quotes inside the brackets are evaluated separately from those around them?

No. What you're giving the shell is three separate tokens:

>"$(echo "

>$foo

and

>")"

Because there is no whitespace in between, it concatenates them to make a single unit:

$(echo $foo)

Then the whole thing is evaluated to get your result.

If you just want to copy the variable though:

result=$foo

Will do the trick.

>>2557

>No. What you're giving the shell is three separate tokens

Wrong.

One of the main benefits of using

$(...)

`...`

"$(echo "$foo")"

"$(...)"

"$foo"

>>2595

indeed. newlines in foo get preserved correctly in

result="$(echo "$foo")"

so the quotes are evaluated correctly. unintuitive but useful.