UNIX for Dummies Questions & Answers

Hello,
I have in my backup folder, files with names convention like this :

Code:

randomFileNames_13-02-2014_23h13m09+1392333189
randomFileNames_14-02-2014_02h13m09+1392343989
randomFileNames_14-02-2014_04h13m09+1392351189

etc....

Base on timestamp at end of the filename, I would to delete all the files which are older than 10 days.
I prefer to base on the timestamp in the file name end NOT on -mtime because those backup files can be access any time for reading.
Thanks for your reading and helps.
Thibault

Hmmm....

You mean something like:

Code:

filename="randomFileNames_13-02-2014_23h13m09+1392333189"
# print - "${filename#*+}"
1392333189

This is based on the assumption that "randomFileNames" will not contain the character "+", otherwise the above might get ambiguous. You might use the above in a manner like:

Code:

ls -1 /path/to/backupdir | while read FILE ; do
     TS="${FILE#*+}"
     if [ $TS -gt $some_int -a $TS -lt $other_int ] ; then   # i.e. range check
          some_command "$FILE"
     fi
done

I hope this helps.

bakunin

Thanks so much for your promt answer.
Yes the randomFileName does not contain the character "+".
May I ask you to explain me about " $TS -gt $some_int -a $TS -lt $other_int " .
Thanks so much.
Thibault

You might want to look at the man page of "test":

-lt: "lower than", checks if value1 is lower than value2
-a: "logical and" connects two conditions with an AND
-gt: "greater than", checks if value1 is greater than value2

So in fact it reads ...if $TS is greater than $some_int AND $TS is lower than $other_int, "some_int > TS > other_int", for short.

I hope this helps.

bakunin

Hello,
Sorry for being late ( a lot of works ).
So your solution works great, but I have an other question relate to path ( something is related to the absolu path of the script ? ) , here my code :

Code:

!/bin/sh
TODAY=`date +%s`
# numbers of day to keep ( 86400 = 1 day )
NDAYS=86400
BCK_DIR=/Volumes/BACKUP/BCK_DATA/_ARCHIVES_/
TRASHDIR=/Volumes/BACKUP/BCK_DATA/Trash/

ls -1 $BCK_DIR | while read FILE ; do
     TS="${FILE#*+}"
	OFFSET=` expr $TODAY - $TS `
     if [ $OFFSET -gt $NDAYS ] ; then   # i.e. range check
          mv "$FILE" "$TRASHDIR"
     fi
done

Here the output :

Code:

mv: rename filetest.txt_19-02-2014_17h58m33+1392829113 to /Volumes/BACKUP/BCK_DATA/Trash/: No such file or directory

So $TRASHDIR is no good but I know how to resolve this.
Any idea

OK, first objection: you should definitely not use backticks any more. They are a B-A-D habit. Use the modern subshell command instead: "$(....)".

Code:

TODAY=$(date +%s)

Perfect would be to type your variables:

Code:

typeset -i TODAY=$(date +%s)

The same goes for for the other variables. Personally (but that is only me) i use a sort-of "hungarian style notation" to keep track of what is in my variables: suffix "i" is for integers, "f" for files/paths, "ch" for characters/strings, etc..
I would write, for instance:

Code:

typeset    fInfile="/path/to/some/file"
typeset -i iToday=1392921191
typeset    chToday="Monday"

Even if i have two different representations for "today" (once a Unix time, once a day of the week) i can tell that "iToday" is an integer and "chToday" holds a string.


Don't do that. I don't mean the backticks this time (you shouldn't use them either, see above), but here you shouldn't forego the capability of any modern shell to deal with integers:

Code:

(( OFFSET = TODAY - TS ))

will do the same and with a lot less effort. It is also easier to read, IMHO.

Well, have a look at the output of ls -1 $BCK_DIR and tell me what you see. The list should look like this:

Code:

# ls -1 /tmp
file1
another.file
yet.another.file
a_file_too
[...]

Do you see any path? I don't. So, inside your loop the variable "FILE" holds only a filename, not the complete path to it, yes? It will hold, for instance,
filetest.txt_19-02-2014_17h58m33+1392829113, but not /Volumes/BACKUP/BCK_DATA/_ARCHIVES_/filetest.txt_19-02-2014_17h58m33+1392829113.

Now, you try to move this file to a certain other location. First problem: you can call this script from anywhere, but chances are the file you looked for in "$BCK_DIR" is not in the current directory. To make your script more robust use:

Code:

     if [ $OFFSET -gt $NDAYS ] ; then
          mv "${BCK_DIR}/${FILE}" "$TRASHDIR"
     fi

Now it will work from anywhere.

Second: you do not take care if "$TRASHDIR" is pointing to any valid directory and if you (or your script) is allowed to write to it. You should check that before you even attempt to move files there:

Code:

if [ ! -d "$TRASHDIR" ] ; then
     print -u2 - "Error: $TRASHDIR does not exist or is not a directory."
     exit 2
fi

Alternatively you could try to create the directory, let the user specify another directory, do whatever - but you should definitely check every step your script undertakes. You do not have to correct every problem, but you should recognize and report it.

The same goes for accessibility: to check if the directory is there is not enough, you have to be able to access it:

Code:

touch "${TRASHDIR}/$$"
if [ $? -gt 0 ] ; then
     print -u2 - "Error: $TRASHDIR cannot be written to."
     exit 2
else
     rm "${TRASHDIR}/$$"
fi

Some (like me) take such cautiousness to religious heights. You could also check: availability of i-nodes, having enough space in the filesystem to copy files there, and a lot of things more. What i show you here is just the basics.

This looks tedious at first, but you will be rewarded with having absolutely unbreakable scripts which never produce an undefined state. They will always be clear about what went wrong and why they were unable to do their task.

I hope this helps.

bakunin

bakunin,
Thanks again so much for taking young time to help me ( and all of the users here...).
It works like a charm now. Here my code :

Code:

#!/bin/sh
DATE=$(date "+%d-%m-%Y_%Hh%Mm%S")
LOG=/Volumes/BACKUP/LOGS/Trash-$DATE.txt

typeset -i TODAY=$(date +%s)
# numbers of day to keep ( 86400 = 1 day )
NDAYS=86400
BCK_DIR=/Volumes/BACKUP/BCK_DATA/_ARCHIVES_
TRASHDIR=/Volumes/BACKUP/Trash

if [ ! -d "$TRASHDIR" ] ; then
     echo "Error: $TRASHDIR does not exist or is not a directory." >> $LOG
     exit 2
fi

touch "${TRASHDIR}/$$"
if [ $? -gt 0 ] ; then
     echo "Error: $TRASHDIR cannot be written to." >>$LOG
     exit 2
else
     rm "${TRASHDIR}/$$"
fi



ls -1 $BCK_DIR | while read FILE ; do
     TS="${FILE#*+}"
	(( OFFSET = TODAY - $TS ))
     if [ $OFFSET -gt $NDAYS ] ; then   # i.e. range check
          #mv "${BCK_DIR}/${FILE}" "${TRASHDIR}/${FILE}"
          mv -v "${BCK_DIR}/${FILE}" "$TRASHDIR" >>$LOG
     fi
done

I don't know why print does not work to output error, so I use echo ( does it matter ? )
And

---------- Post updated at 04:20 PM ---------- Previous update was at 04:16 PM ----------

Bakunin,
I learned so much thanks to you, I'll like to learn more about "modern shell".
Can you please point me to some clues where to start.
Thanks again
Thibault