51
votes
3answers
24k views

Quoting within $(command substitution) in Bash

In my Bash environment I use variables containing spaces, and I use these variables within command substitution. Unfortunately I cannot find the answer on SE. What is the correct way to quote my ...
37
votes
1answer
9k views

When is double-quoting necessary?

The old advice used to be to double-quote any expression involving a $VARIABLE, at least if one wanted it to be interpreted by the shell as one single item, otherwise, any spaces in the content of $...
15
votes
2answers
2k views

Are quotes needed for local variable assignment?

Can I safely omit quotes on the right side of a local assignment? function foo { local myvar=${bar} stuff() } I'm mainly interested in bash, but any info on corner cases in other shells are ...
10
votes
3answers
49k views

How can I concatenate a shell variable to other other parameters in my command lines?

How can I concatenate a shell variable to other other parameters in my command lines ? For example, #!/bin/sh WEBSITE="danydiop" /usr/bin/mysqldump --opt -u root --ppassword $WEBSITE > $WEBSITE....
8
votes
7answers
6k views

Splitting large directory tree into specified-size chunks?

I have a directory tree that I would like to back up to optical disks. Unfortunately, it exceeds the size of any one disk (it's about 60GB). I am looking for a script that would split this tree into ...
7
votes
3answers
2k views

What is the difference having double quotes or not in bash [duplicate]

I have some bash scripts, one which has the following content: #!/bin/bash source $(dirname ${BASH_SOURCE[0]})/script.sh while the other one has the following content: #!/bin/bash source "$(...
5
votes
2answers
393 views

Bash, curious about echo $variable

I was hacking at a small script earlier and noticed something I can't explain. Running this command (time wget --spider http://www.google.co.uk/) 2>&1 | egrep 'real|response' gives me ...
5
votes
3answers
5k views

Why the double quotes and backquotes in a shell script?

I'm looking at this script mysql backup script and I don't understand what is the reason for using both backticks and double quotes around command names? 379 WHICH="`which which`" 380 AWK="`${WHICH} ...
5
votes
3answers
2k views

Quote a variable in shell script “if” statement

e.g. if [ "$FOO" = "true" ]; then vs if [ $FOO = "true" ]; then What is the different? Seems both of two statements also works.
4
votes
1answer
319 views

Any problem assigning one variable to another in shell without using quotes? [duplicate]

This question is about assigning the entire contents of one variable to another variable. Variable is not being used (sent to echo, etc.) No parameter expansion is being done during the assignment. ...
4
votes
2answers
877 views

Shell Script to isolate files scattered in different folders

I need to write a shell script that traverses a given directory structure in multiple levels, recognizes the video files scattered in the folders and copies all of them to another single folder. The ...
3
votes
2answers
316 views

open a file using CDPATH and symlink

To quickly move around, I added a path to CDPATH that contains symlinks to different locations. I did this by adding the following line to .bashrc: export CDPATH=~/symlinks When working with ...
3
votes
1answer
2k views

Printf formatting with variable format - what does this var reference?

I am experimenting with printf formatting in bash and I ran across this piece of code: #/bin/bash divider=============================== divider=$divider$divider header="\n %-15s %8s %10s %11s\n" ...
3
votes
2answers
290 views

Bind locally installed library

I have no root-acces on a machine and i'm trying to install a library called GiNaC locally in my home folder. I use this tutorial http://www.ginac.de/tutorial/Configuration.html#Configuration. At the ...
2
votes
2answers
312 views

What is PATH on a Mac OS?

What is the PATH in a Mac OS? I have used it to install global command-line tools, but the only documentation I have found are tutorials for doing just that, with no real explanation of what is ...

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