Scenario: I have a script but no idea where I am in the directory tree, I need to resolve back to the nearest known location UPROC[something]
What I have so far:
I have a script running in a directory for example:
/home/jim/query/UPROCL/test/bob/dircut.sh
now the only constant in this is that the Directory I want will begin with UPROC... maybe not UPROCL but definitely UPROC
So I have written the following:
#!/bin/bash
#Absolute path for this script
SCRIPT=$(readlink -f "$0")
echo $SCRIPT
#Gets Path of script without script name
SCRIPTPATH=$(dirname "$SCRIPT")
echo $SCRIPTPATH
#Cuts everything after UPROC(.* is wildcard)/
CUTDOWN=$(sed 's/\(UPROC.*\/\).*/\1/' <<< $SCRIPTPATH)
echo $CUTDOWN
The only problem is that it output is:
/home/jim/query/UPROCL/test/bob/dircut.sh
/home/jim/query/UPROCL/test/bob
/home/jim/query/UPROCL/test/
Can some tell me what is wrong with my sed command as it is not cutting down to
/home/jim/query/UPROCL/
Because * is greedy. You want to be more selective about what characters are allowed following "UPROC" -- any non-slash
Not
sed 's/\(UPROC.*\/\).*/\1/'
but
sed -r 's,(UPROC[^/]*/).*,\1,'
Using different delimiters for the s/// command reduces the "leaning toothpick" problem.
Because the .* in the () is matching to the / at the end of test/.
You need [^/]* instead of . to not match any slashes.
When you want to know in which directory you are, why don't use pwd?
One thing which might be useful: the command pwd shows the value of the environment variable PWD (uppercase). In case you want to use the current directory as a value, you might use this.
Related
I'am new in Linux and I want to write a bash script that can read in a file name of a directory that starts with LED + some numbers.(Ex.: LED5.5.002)
In that directory there is only one file that will starts with LED. The problem is that this file will every time be updated, so the next time it will be for example LED6.5.012 and counting.
I searched and tried a little bit and came to this solution:
export fspec=/home/led/LED*
LedV=`basename $fspec`
echo $LedV
If I give in those commands one by one in my terminal it works fine, LedV= LED5.5.002 but if i run it in a bash scripts it gives the result: LedV = LED*
I search after another solution:
a=/home/led/LED*
LedV=$(basename $a)
echo $LedV
but here again the same, if i give it in one by one it's ok but in a script: LedV = LED*.
It's probably something small but because of my lack of knowledge over Linux I cannot find it. So can someone tell what is wrong?
Thanks! Jan
Shell expansions don't happen on scalar assignments, so in
varname=foo*
the expansion of "$varname" will literally be "foo*". It's more confusing when you consider that echo $varname (or in your case basename $varname; either way without the double quotes) will cause the expansion itself to be treated as a glob, so you may well think the variable contains all those filenames.
Array expansions are another story. You might just want
fspec=( /path/LED* )
echo "${fspec[0]##*/}" # A parameter expansion to strip off the dirname
That will work fine for bash. Since POSIX sh doesn't have arrays like this, I like to give an alternative approach:
for fspec in /path/LED*; do
break
done
echo "${fspec##*/}"
pwd
/usr/local/src
ls -1 /usr/local/src/mysql*
/usr/local/src/mysql-cluster-gpl-7.3.4-linux-glibc2.5-x86_64.tar.gz
/usr/local/src/mysql-dump_test_all_dbs.sql
if you only have 1 file, you will only get 1 result
MyFile=`ls -1 /home/led/LED*`
Example bash script demonstrating my problem:
#!/bin/bash
function exclude
{
BACKUP_EXCLUDES="$BACKUP_EXCLUDES --exclude=\"$1\""
}
exclude "/proc"
exclude "/dev"
exclude "/mnt"
exclude "/media"
exclude "/lost+found"
echo $BACKUP_EXCLUDES
Output:
--exclude="/proc" --exclude="/dev" --exclude="/mnt" --exclude="/media" --exclude="/lost+found"
Perfect! But when I try adding:
rsync -ruvz $BACKUP_EXCLUDES / /some/backup/path
$BACKUP_EXCLUDES is completely ignored with no errors or warnings... Why?
you need to use array:
#!/usr/bin/env bash
BACKUP_EXCLUDES=()
function exclude
{
while
(( $# ))
do
BACKUP_EXCLUDES+=(--exclude="$1")
shift
done
}
exclude /proc /dev /mnt /media
exclude "/lost+found"
rsync -ruvz "${BACKUP_EXCLUDES[#]}" / /some/backup/path
the bash explanation: please check #janos answer
the zsh explanation (if it was Zsh): when you used a string variable it was like you passed --exclude="\"/proc\" --exclude=\"/media\" ..." - so it was treated as long path with spaces - which never matched.
It doesn't work because the quotes are included in the individual --exclude parameters. That is, rsync will ignore "/proc" instead of /proc. Of course "/proc" (with quotes) doesn't exist.
If you stick an eval in front of the command it will work, like this:
eval rsync -ruvz $BACKUP_EXCLUDES / /some/backup/path
In this case the --exclude="/proc" (and all others) will be evaluated to --exclude=/proc, that's why it will work.
But I think you should use arrays as proposed by #mpapis, or --exclude-from=FILE as proposed by a comment. Both are much better and cleaner solutions.
Today I tried a script in linux to get all files in one dir. It was pretty straightforward, but I found something interesting.
#!/bin/bash
InputDir=/home/XXX/
for file in $InputDir'*'
do
echo $file
done
The output is:
/home/XXX/fileA /home/XXX/fileB
But when I just input the dir directly, like:
#!/bin/bash
InputDir=/home/XXX/
for file in /home/XXX/*
do
echo $file
done
The output is:
/home/XXX/fileA
/home/XXX/fileB
It seems, in the first script, there was only one loop and all the file names were stored in the variable $file in the FIRST loop, separated by space. But in the second script, one file name was stored in $file just in one loop, and there were more than one loop. What is exactly the difference between these two scripts?
Thanks very much, maybe my question is a little bit naive..
The behavior is correct and "as expected".
for file in $InputDir'*' means assign "/home/XXX/*" to $file (note the quotes). Since you quoted the asterisk, it will not be executed at this time. When the shell sees echo $file, it first expands the variables and then it does glob expansion. So after the first step, it sees
echo /home/XXX/*
and after glob expansion, it sees:
echo /home/XXX/fileA /home/XXX/fileB
Only now, it will execute the command.
In the second case, the pattern /home/XXX/* is expanded before the for is executed and thus, each file in the directory is assigned to file and then the body of the loop is executed.
This will work:
for file in "$InputDir"*
but it's brittle; it will fail, for example, when you forget to add a / to the end of the variable $InputDir.
for file in "$InputDir"/*
is a little bit better (Unix will ignore double slashes in a path) but it can cause trouble when $InputDir is not set or empty: You'll suddenly list files in the / (root) folder. This can happen, for example, because of a typo:
inputDir=...
for file in "$InputDir"/*
Case matters on Unix :-)
To help you understand code like this, use set -x ("enable tracing") in a line before the code you want to debug.
The difference is the quoting of '*'. In the first case the loop only executes once, with $file equal to /home/XXX/* which then expands to all the files in the directory when passed to echo. In the second case it executes once per file, with $file equal to each file name in turn.
Bottom line - change:
for file in $InputDir'*'
to:
for file in $InputDir*
or, better, and to make it more readable - change:
InputDir=/home/XXX/
for file in $InputDir'*'
to:
InputDir=/home/XXX
for file in $InputDir/*
I am experimenting with wildcards in bash and tried to list all the files that start with "xyz" but does not end with ".TXT" but getting incorrect results.
Here is the command that I tried:
$ ls -l xyz*[!\.TXT]
It is not listing the files with names "xyz" and "xyzTXT" that I have in my directory. However, it lists "xyz1", "xyz123".
It seems like adding [!\.TXT] after "xyz*" made the shell look for something that start with "xyz" and has at least one character after it.
Any ideas why it is happening and how to correct this command? I know it can be achieved using other commands but I am especially interested in knowing why it is failing and if it can done just using wildcards.
These commands will do what you want
shopt -s extglob
ls -l xyz!(*.TXT)
shopt -u extglob
The reason why your command doesn't work is beacause xyz*[!\.TXT] which is equivalent to xyz*[!\.TX] means xyz followed by any sequence of character (*) and finally a character in set {!,\,.,T,X} so matches 'xyzwhateveryouwant!' 'xyzwhateveryouwant\' 'xyzwhateveryouwant.' 'xyzwhateveryouwantT' 'xyzwhateveryouwantX'
EDIT: where whateveryouwant does not contain any of !\.TX
I don't think this is doable with only wildcards.
Your command isn't working because it means:
Match everything that has xyz followed by whatever you want and it must not end with sequent character: \, .,T and X. The second T doesn't count as far as what you have inside [] is read as a family of character and not as a string as you thought.
You don't either need to 'escape' . as long as it has no special meaning inside a wildcard.
At least, this is my knowledge of wildcards.
i have a directory with a lot of subdirectories with a # infront of them:
#adhasdk
#ad18237
I want to rename them all and remove the # caracter
I tried to do:
rename -n `s/#//g` *
but didn't seem to work.
-bash: s/#//g: No such file or directory
Any ideas on this.
Thanks
Just use
$ rename 's/^#//' *
use -n just to check that what you think it would happen really happens.
In you example you have the clue about the wrong quotes used (backticks) in the error message
-bash: s/#//g: No such file or directory
bash is trying to execute a command named s/#//g.
No that using g (global) and not anchoring the regular expression you will replace any #, not just the one in the first position.
I don't know whether it's just a typo when you typed it here, but that "rename" command should work if:
you leave off the "-n" and
you quote the substitution with regular single-quotes and not back-quotes
The "-n" tells it to not really do anything. The back-quotes are just wrong (they mean something but not what you want here).
The problem is that you use backticks (`). You should use normal quotes:
rename -n 's/#//g' *
for DIR in \#*/
do
echo mv "$DIR" "${DIR/#\#/}"
done
I had to rename all folders inside a given folder. Each folder name had some text inside round braces. The following command removed the round braces from all folder names:
rename 's/(.+)//' *
Some distros doesn't support regexp in rename. You have to install prename. Even more, sometimes you can't install prename and you have to install gprename to have binary prename.
If you have 'prename' then just change backtick character " ` " to single quote and everything should work.
So the solution should be:
prename -n 's/#//g' *
or
prename -n 'y/#//' *