What is this flag?
if (-M ..filepath..)
what is the '-M' flag?
perldoc -f -M will answer your question...
This is the modification "age" of the file, in fractional days. That is, it is the number of days since the file was modified, as of the script start time (or as of some other time, if you explicitly set the $^T variable).
I sure hope that the actual code is along the lines of -M filepath > ...; just testing -M's result for truth is pointless.
Script start time minus file modification time (aka file modification age), in days.
In other words, it returns the age of OPERAND in days when the program started.
Also see a full list of file test operators in perldoc perlfunc (-X section)
Modification age (measured in days)
from http://www.devshed.com/c/a/Perl/File-Tests-in-Perl/
if we have something like this:
$age = -M FILE;
$age will contain the days since the file was modified.
Related
I'm writting some zsh functions using the powerful completion feature. The computation of my completions take some times and I want to make use of the completion caching policy. From the zsh manual (https://zsh.sourceforge.io/Doc/Release/Completion-System.html) I found this code snippet
example_caching_policy () {
# rebuild if cache is more than a week old
local -a oldp
oldp=( "$1"(Nm+7) )
(( $#oldp ))
}
I couldn't find any explanation on the (Nm+7) syntax, what does Nm means ? With try and error I could find out that for example Nms+1 would change the cache policy to 1 second, while Nmh+1 to 1 hour. But where can I find the general (NmX+N) construct explanation ?
Same what does exactly means the line (( $#oldp )) ?
I can explain the (Nm+7)
man zshexpn, search for Glob Qualifiers
a[Mwhms][-|+]n
files accessed exactly n days ago. Files accessed within the last n days are selected using a negative
value for n (-n). Files accessed more than n days ago are selected by a positive n value (+n). Op‐
tional unit specifiers `M', `w', `h', `m' or `s' (e.g. `ah5') cause the check to be performed with
months (of 30 days), weeks, hours, minutes or seconds instead of days, respectively. An explicit `d'
for days is also allowed.
Any fractional part of the difference between the access time and the current part in the appropriate
units is ignored in the comparison. For instance, `echo *(ah-5)' would echo files accessed within the
last five hours, while `echo *(ah+5)' would echo files accessed at least six hours ago, as times
strictly between five and six hours are treated as five hours.
m[Mwhms][-|+]n
like the file access qualifier, except that it uses the file modification time.
N stands for NULL_GLOB, if zsh matches nothing, it will remove the pattern.
Without this N option, if it matches nothing it will print an error.
Example with 4 files
$ touch lal # = updates file modification date to now
$ ls
lal lil lol tut
$ ls l*(m+7)
lil lol
# files older than 7 days starting with l
$ ls l*(m-7)
lal
# files younger than 7 days starting with l
$ ls l*(m+200)
zsh: no match
# no files older than 200 days
$ ls l*(Nm+200)
lal lil lol tut
# N = NULL_GLOB made disappear the non-matching pattern so it's just ls
-- Edit : Resolved. See answer.
Background:
I'm writing a shell that will perform some extra actions required on our system when someone resizes a database.
The shell is written in ksh (requirement), the OS is Solaris 5.10 .
The problem is with one of the checks, which verifies there's enough free space on the underlying OS.
Problem:
The check reads the df -k line for root, which is what I check in this step, and prints it to a file. I then "read" the contents into variables which I use in calculations.
Unfortunately, when I try to run an arithmetic operation on one of the variables, I get an error indicating it is null. And a debug output line I've placed after that line verifies that it is null... It lost it's value...
I've tried every method of doing this I could find online, they work when I run it manually, but not inside the shell file.
(* The file does have #!/usr/bin/ksh)
Code:
df -k | grep "rpool/ROOT" > dftest.out
RPOOL_NAME=""; declare -i TOTAL_SIZE=0; USED_SPACE=0; AVAILABLE_SPACE=0; AVAILABLE_PERCENT=0; RSIGN=""
read RPOOL_NAME TOTAL_SIZE USED_SPACE AVAILABLE_SPACE AVAILABLE_PERCENT RSIGN < dftest.out
\rm dftest.out
echo $RPOOL_NAME $TOTAL_SIZE $USED_SPACE $AVAILABLE_SPACE $AVAILABLE_PERCENT $RSIGN
((TOTAL_SIZE=$TOTAL_SIZE/1024))
This is the result:
DBResize.sh[11]: TOTAL_SIZE=/1024: syntax error
I'm pulling hairs at this point, any help would be appreciated.
The code you posted cannot produce the output you posted. Most obviously, the error is signalled at line 11 but you posted fewer than 11 lines of code. The previous lines may matter. Always post complete code when you ask for help.
More concretely, the declare command doesn't exist in ksh, it's a bash thing. You can achieve the same result with typeset (declare is a bash equivalent to typeset, but not all options are the same). Either you're executing this script with bash, or there's another error message about declare, or you've defined some additional commands including declare which may change the behavior of this code.
None of this should have an impact on the particular problem that you're posting about, however. The variables created by read remain assigned until the end of the subshell, i.e. until the code hits a ), the end of a pipe (left-hand side of the pipe only in ksh), etc.
About the use of declare or typeset, note that you're only declaring TOTAL_SIZE as an integer. For the other variables, you're just assigning a value which happens to consist exclusively of digits. It doesn't matter for the code you posted, but it's probably not what you meant.
One thing that may be happening is that grep matches nothing, and therefore read reads an empty line. You should check for errors. Use set -e in scripts to exit at the first error. (There are cases where set -e doesn't catch errors, but it's a good start.)
Another thing that may be happening is that df is splitting its output onto multiple lines because the first column containing the filesystem name is too large. To prevent this splitting, pass the option -P.
Using a temporary file is fragile: the code may be executed in a read-only directory, another process may want to access the same file at the same time... Here a temporary file is useless. Just pipe directly into read. In ksh (unlike most other sh variants including bash), the right-hand side of a pipe runs in the main shell, so assignments to variables in the right-hand side of a pipe remain available in the following commands.
It doesn't matter in this particular script, but you can use a variable without $ in an arithmetic expression. Using $ substitutes a string which can have confusing results, e.g. a='1+2'; $((a*3)) expands to 7. Not using $ uses the numerical value (in ksh, a='1+2'; $((a*3)) expands to 9; in some sh implementations you get an error because a's value is not numeric).
#!/usr/bin/ksh
set -e
typeset -i TOTAL_SIZE=0 USED_SPACE=0 AVAILABLE_SPACE=0 AVAILABLE_PERCENT=0
df -Pk | grep "rpool/ROOT" | read RPOOL_NAME TOTAL_SIZE USED_SPACE AVAILABLE_SPACE AVAILABLE_PERCENT RSIGN
echo $RPOOL_NAME $TOTAL_SIZE $USED_SPACE $AVAILABLE_SPACE $AVAILABLE_PERCENT $RSIGN
((TOTAL_SIZE=TOTAL_SIZE/1024))
Strange...when I get rid of your "declare" line, your original code seems to work perfectly well (at least with ksh on Linux)
The code :
#!/bin/ksh
df -k | grep "/home" > dftest.out
read RPOOL_NAME TOTAL_SIZE USED_SPACE AVAILABLE_SPACE AVAILABLE_PERCENT RSIGN < dftest.out
\rm dftest.out
echo $RPOOL_NAME $TOTAL_SIZE $USED_SPACE $AVAILABLE_SPACE $AVAILABLE_PERCENT $RSIGN
((TOTAL_SIZE=$TOTAL_SIZE/1024))
print $TOTAL_SIZE
The result :
32962416 5732492 25552588 19% /home
5598
Which are the value a simple df -k is returning. The variables seem to last.
For those interested, I have figured out that it is not possible to use "read" the way I was using it.
The variable values assigned by "read" simply "do not last".
To remedy this, I have applied the less than ideal solution of using the standard "while read" format, and inside the loop, echo selected variables into a variable file.
Once said file was created, I just "loaded" it.
(pseudo code:)
LOOP START
echo "VAR_A="$VAR_A"; VAR_B="$VAR_B";" > somefile.out
LOOP END
. somefile.out
First of all, I'm very new to programming and so would need your help in writing a perl script to do the following on windows.
I have a big log file with timestamp (1gb) and its difficult to read the logs as it takes a lot of time to open. so my requirement is to copy the logs from the bigger log file for the last one hour and paste it to another file and then copy the next 1 hr of data to different file(so we will have 24 files for a day). The next day the data in these files needs to be over written or delete & create a new file.
Sample log :
09092016-00:02:00,..................
09092016-00:02:08,..................
09092016-00:02:15,..................
09092016-00:02:18,..................
Please help me with this and thanks for your help in advance.
Thanks,
A simpler solution would be to use the split command to split the files into manageable sizes.
split -l 1000 logfile
Will split your logfile into smaller files of 1000 lines each.
You can then just use grep to find the files that contain the day you need.
grep 09092016 logfile*
for example:
logfile="./log"
while read -r d m y h; do
grep "^$d$m$y-$h" "$logfile" > "partial-${y}${m}{$d}-${h}.log"
done < <(sed -n 's/\(..\)\(..\)\(....\)-\(..\)\(.*\)/\1 \2 \3 \4/p' "$logfile" | sort -u)
easy, but not efficient. It reads the whole big logfile 25x for the split. (1x for gathering the existing ddmmyyyy-hh lines in the log, and again for every different found date-hour.)
I am trying to create my first zsh completion script, in this case for the command netcfg.
Lame as it may sound I have stuck on the first hurdle, disclaimer, I know how to do this crudely, however I seek the "ZSH WAY" to do this.
I need to list the files in /etc/networking but only the files, not the directory component, so I do the following.
echo $(ls /etc/network.d/*(.))
/etc/network.d/ethernet-dhcp /etc/network.d/wireless-wpa-config
What I wanted was:
ethernet-dhcp wireless-wpa-config
So I try (excuse my naivity) :
echo ${(s/*\/)$(ls /etc/network.d/*(.))}
/etc/network.d/ethernet-dhcp /etc/network.d/wireless-wpa-config
It seems that this doesn't work, I'm sure there must be some clever way of doing this by splitting into an array and getting the last part but as I say, I'm complete noob at this.
Any advice gratefully received.
General note: There is no need to use ls to generate the filenames. You might as well use echo some*glob. But if you want to protect the possible embedded newline characters even that is a bad idea. The first example below globs directly into an array to protect embedded newlines. The second one uses printf to generate NUL terminated data to accomplish the same thing without using a variable.
It is easy to do if you are willing to use a variable:
typeset -a entries
entries=(/etc/network.d/*(.)) # generate the list
echo ${entries#/etc/network.d/} # strip the prefix from each one
You can also do it without a variable, but the extra stuff to isolate individual entries is a bit ugly:
# From the inside, to the outside:
# * glob the entries
# * NUL terminate them into a single string
# * split at NUL
# * strip the prefix from each one
echo ${${(0)"$(printf '%s\0' /etc/network.d/*(.))"}#/etc/network.d/}
Or, if you are going to use a subshell anyway (i.e. the command substitution in the previous example), just cd to the directory so it is not part of the glob expansion (plus, you do not have to repeat the directory name):
echo ${(0)"$(cd /etc/network.d && printf '%s\0' *(.))"}
Chris Johnsen's answer is full of useful information about zsh, however it doesn't mention the much simpler solution that works in this particular case:
echo /etc/network.d/*(:t)
This is using the t history modifier as a glob qualifier.
Thanks for your suggestions guys, having done yet more reading of ZSH and coming back to the problem a couple of days later, I think I've got a very terse solution which I would like to share for your benefit.
echo ${$(print /etc/network.d/*(.)):t}
I'm used to seeing basename(1) stripping off directory components; also, you can use echo /etc/network/* to get the file listing without running the external ls program. (Running external programs can slow down completion more than you'd like; I didn't find a zsh-builtin for basename, but that doesn't mean that there isn't one.)
Here's something I hope will help:
haig% for f in /etc/network/* ; do basename $f ; done
if-down.d
if-post-down.d
if-pre-up.d
if-up.d
interfaces
Cygwin user here (though if there's a suitable solution I will carry it over to K/Ubuntu, which I also use).
I have a Welcome message in my .bashrc that looks like the following:
SAD=(`date +%A-%B-%d-%Y`)
DUB=(`date -u +%k:%M`)
printf "Today's Date is: ${SAD}.\n"
printf "Dublin time is now ${DUB}. (24-Hour Clock)\n"
After numerous attempts to use whitespaces in the variable SAD above, I gave in and used hyphens. But I am, understandably, not satisfied with this band-aid solution. The problem, as I recall, was that every time I tried using quoted space, \s or some similar escape tag, along with the variables listed in the appropriate section of the GNU manpage for date, the variable for Year was either ignored or returned an error. What I do'nt want to have to do is resort to the full string as returned by date, but rather to keep the order in which I have things in the code above.
As I write this, it occurs to me that setting the IFS around this code for the Welcome message may work, provided I return it to defaults afterwards (the above appears at lines 13-17 of a 68-line .bashrc). However, I can't recall how to do that, nor am I sure that it would work.
Generally-speaking, .bashrc files are in valid BASH syntax, aren't they? Mine certainly resemble the scripts I've either written myself or tested from other sources. All I'm missing, I suppose, is the code for setting and unsetting the field separators around this message block.
No doubt anyone who comes up with a solution will be doing a favor not only to me, but to any other relative newbies on the Net taking their first (or thirteenth through seventeenth) steps in the world of shell scripting.
BZT
Putting
SAD=$(date "+%A %B %d %Y")
DUB=$(date -u +%k:%M)
echo "Today's Date is: ${SAD}."
echo "Dublin time is now ${DUB}. (24-Hour Clock)"
in my .bash_profile prints
Today's Date is: Thursday February 18 2010.
Dublin time is now 12:55. (24-Hour Clock)
I think that's what you want.
the problem is your array declaration.
SAD=(date +%A-%B-%d-%Y) just means you are putting the string "date" as element 0, and "+%A-%B-%d-%Y" as element 1. see for yourself
$ SAD=(date +%A-%B-%d-%Y) #<-- this is an array declaration
$ echo ${SAD[0]}
date
$ echo ${SAD[1]}
+%A-%B-%d-%Y
if you want the value of "date" command to be in a variable, use $(..), eg
$ SAD=$(date +%A-%B-%d-%Y)
$ echo ${SAD}
Thursday-February-18-2010
To get spaces, you need to quote the argument to date so that it's a single string. You're also erroneously declaring SAD and DUB as arrays, when what you really meant to do was evaluate them. Try this:
[/tmp]> $(date "+%A %B %d, %Y")
Thursday February 18, 2010
date +%A\ %B\ %d\ %Y
I found the combination that works:
SAD=$(date "+%A %B %d %Y")
echo $SAD
Thursday February 18 2010
Yet another instance when:
It pays to ask a question
It helps to know where to put your double quotes.
date obviously does not know from quoted space, but Bash does, so
it's a matter of "whispering in the right ear."
Thank you ghostdog74.
BZT