perl -E '$i=#{[`zypper lr`]}-2;map{`zypper rr $_`}1..$i'
What would be a good way to write this perl-onliner in bash. ( I would like to remove all repositores with zypper)?
Here's a way to do this:
The first command counts the number of lines produced by zypper lr command.
So, you obtain that by:
COUNT_LINES=`zypper lr|tail +3|wc -l`
The second command merely runs zypper rr [NUMBER] for each number 1 through the counter; so you run the for loop in bash as shown in this SO question:
How do I iterate over a range of numbers in bash?
zypper lr | grep -P "^\d" | cut -d'|' -f 1 | xargs sudo zypper rr
But much easier to simply:
sudo rm -rf /etc/zypp/repos.d/*
Related
Well known commands like make, rsync, and, git use -n option for dry-run.
What does -n stand for in this context?
My guess is that it's because dry-run contains the letter n and because d and r are already used:
$ make --help | grep '^ *-[dr]'
-d Print lots of debugging information.
-r, --no-builtin-rules Disable the built-in implicit rules.
$ rsync --help | grep '^ *-[dr]'
-r, --recursive recurse into directories
-d, --dirs transfer directories without recursing
I want to filter the output of the blkid to get the UUID.
The output of blkid looks like
CASE 1:-
$ blkid
/dev/sda2: LABEL="A" UUID="4CC9-0015"
/dev/sda3: LABEL="B" UUID="70CF-169F"
/dev/sda1: LABEL=" NTFS_partition" UUID="3830C24D30C21234"
In somecases the output of blkid looks like
CASE 2:-
$ blkid
/dev/sda1: UUID="d7ec380e-2521-4fe5-bd8e-b7c02ce41601" TYPE="ext4"
/dev/sda2: UUID="fc54f19a-8ec7-418b-8eca-fbc1af34e57f" TYPE="ext4"
/dev/sda3: UUID="6f218da5-3ba3-4647-a44d-a7be19a64e7a" TYPE="swap"
I want to filter out the UUID.
Using the combination of grep and cut it can be done as
/sbin/blkid | /bin/grep 'sda1' | /bin/grep -o -E 'UUID="[a-zA-Z|0-9|\-]*' | /bin/cut -c 7-
I have tried using awk , grep and cut as below for filtering the UUID
$ /sbin/blkid | /bin/grep 'sda1' | /usr/bin/awk '{print $2}' | /bin/sed 's/\"//g' | cut -c 7-
7ec380e-2521-4fe5-bd8e-b7c02ce41601
The above command(which uses awk) is not reliable since sometimes an extra field such as LABEL may be present in the output of the blkid program as shown in the above output.
What is the best way to create a command using awk which works reliably?
Please post if any other elegant method exits for the job using bin and core utils. I dont want to use perl or python since this has to be run on busybox.
NOTE:-I am using busybox blkid to which /dev/sda1 can not be passed as the args(the version i am using does not support it) hence the grep to filter the line.
UPDATE :- added the CASE 2: -output to show that field position can not be relied upon.
Why are you making it so complex?
Try this:
# blkid -s UUID -o value
d7ec380e-2521-4fe5-bd8e-b7c02ce41601
fc54f19a-8ec7-418b-8eca-fbc1af34e57f
6f218da5-3ba3-4647-a44d-a7be19a64e7a
Or this:
# blkid -s UUID -o value /dev/sda1
d7ec380e-2521-4fe5-bd8e-b7c02ce41601
Install proper blkid package if you don't have it:
sudo apt-get install util-linux
sudo yum install util-linux
For all the UUID's, you can do :
$ blkid | sed -n 's/.*UUID=\"\([^\"]*\)\".*/\1/p'
d7ec380e-2521-4fe5-bd8e-b7c02ce41601
fc54f19a-8ec7-418b-8eca-fbc1af34e57f
6f218da5-3ba3-4647-a44d-a7be19a64e7a
Say, only for a specific sda1:
$ blkid | sed -n '/sda1/s/.*UUID=\"\([^\"]*\)\".*/\1/p'
d7ec380e-2521-4fe5-bd8e-b7c02ce41601
The sed command tries to group the contents present within the double quotes after the UUID keyword, and replaces the entire line with the token.
Here's a short awk solution:
blkid | awk 'BEGIN{FS="[=\"]"} {print $(NF-1)}'
Output:
4CC9-0015
70CF-169F
3830C24D30C21234
Explanation:
BEGIN{FS="[=\"]"} : Use = and " as delimiters
{print $(NF-1)}: NF stands of Number of Fields; here we print the 2nd to last field
This is based on the consistent structure of blkid output: UUID in quotes is at the end of each line.
Alternatively:
blkid | awk 'BEGIN{FS="="} {print $NF}' | sed 's/"//g'
data.txt
/dev/sda2: LABEL="A" UUID="4CC9-0015"
/dev/sda3: LABEL="B" UUID="70CF-169F"
/dev/sda1: LABEL=" NTFS_partition" UUID="3830C24D30C21234"
awk and sed combination
cat data.txt | awk 'BEGIN{FS="UUID";RS="\n"} {print $2}' | sed -e 's/=//' -e 's/"//g'
Explanation:
Set the Field Separator to the string 'UUID', $2 will give the rest output
use sed then to remove the = and " as shown where -e is a switch so that you can give multiple sed commands/expression in one.
All occurrences of " are removed using the ending g option i.e. global.
The question has a "e.t.c" so I'm going to assume python is one of the options ;)
#!/usr/bin/env python3
import subprocess, re, json
# get blkid output
blkid = subprocess.check_output(["blkid"]).decode('utf-8')
devices = []
for line in [x for x in blkid.split('\n') if x]:
parameters = line.split()
for idx, parameter in enumerate(parameters):
if idx is 0:
devices.append({"DEVICE": re.sub(r':$','',parameter)})
continue
key_and_value = parameter.split('=')
devices[-1].update({
key_and_value[0]: re.sub(r'"','',key_and_value[1])
})
uuids = [{dev['DEVICE']: dev['UUID']} for dev in devices if 'UUID' in dev.keys()]
print(json.dumps(uuids, indent=4, sort_keys=True))
Although, this is probably overkill and quite a few error handling/optimization is missing from this script XD
I assume you're using busybox in an initramfs and you are waiting for your e.g. USB drive with the rootfs on it to become available.
You could use the following awk script (busybox awk compliant).
# cat get-ruuid.awk
BEGIN {
ruuid=ENVIRON["RUUID"]
}
/^\/dev\/sd[a-z]/ {
if (index($0, tolower(ruuid)) || index($0, toupper(ruuid))) {
split($1, parts, ":")
printf("%s\n", parts[1])
exit(0) # Return success and stop further scanning.
}
}
END {
exit(1) # If we reach the end, it means RUUID was not found.
}
Call it as follows from e.g. the init script; this is not the most ideal way.
# The UUID of your root partition
export RUUID="<put proper uuid value here>"
for x in 1, 2, 3, 4, 5 ; do
mdev -s
found=$(blkid | awk -f ./get-ruuid.awk)
test -z $found || break; # If no longer zero length, break the loop.
sleep 1
done
But if this is the only reason why you would want to have an initramfs, I would use the 'root=PARTUUID=... waitroot' Linux kernel command line option. Check the kernel docs and sources.
Get the proper PARTUUID (NOT UUID) of your root partition with the blkid command.
The terminal transcript speaks for itself:
iMac:~$ echo -n a | md5
0cc175b9c0f1b6a831c399e269772661
iMac:~$ perl -e 'system "echo -n a | md5"'
c3392e9373ccca33629d82b17699420f
Note that the MD5 hash of a is 0cc175b9c0f1b6a831c399e269772661, the first
result. Why does it turns out to be different when the same command is called
by perl?
By the way, perl is perl 5, version 12, subversion 4 (v5.12.4) built for darwin-thread-multi-2level. And the system: Mac OS 10.8, Darwin 12.0
When in the /bin/sh shell on mac, echo -n doesn't not print out the newline like it does in /bin/bash. You can see this if you drop into /bin/sh and run echo -n a, your output should look like this:
sh-3.2$ echo -n a
-n a
so you're literally getting -n a instead of the desired a. As perl system runs /bin/sh to evaluate your command, -n a is being passed into md5 instead of your desired a
The specific question has already been answered, but I want to point out that od is useful to help understand exactly what any command outputs or file contains. This is useful especially to show otherwise non-printing characters.
$ echo -n a | od -tc
0000000 a
0000001
$ perl -e 'system "echo -n a | od -tc";'
0000000 - n a \n
0000005
The following command is correctly changing the contents of 2 files.
sed -i 's/abc/xyz/g' xaa1 xab1
But what I need to do is to change several such files dynamically and I do not know the file names. I want to write a command that will read all the files from current directory starting with xa* and sed should change the file contents.
I'm surprised nobody has mentioned the -exec argument to find, which is intended for this type of use-case, although it will start a process for each matching file name:
find . -type f -name 'xa*' -exec sed -i 's/asd/dsg/g' {} \;
Alternatively, one could use xargs, which will invoke fewer processes:
find . -type f -name 'xa*' | xargs sed -i 's/asd/dsg/g'
Or more simply use the + exec variant instead of ; in find to allow find to provide more than one file per subprocess call:
find . -type f -name 'xa*' -exec sed -i 's/asd/dsg/g' {} +
Better yet:
for i in xa*; do
sed -i 's/asd/dfg/g' $i
done
because nobody knows how many files are there, and it's easy to break command line limits.
Here's what happens when there are too many files:
# grep -c aaa *
-bash: /bin/grep: Argument list too long
# for i in *; do grep -c aaa $i; done
0
... (output skipped)
#
You could use grep and sed together. This allows you to search subdirectories recursively.
Linux: grep -r -l <old> * | xargs sed -i 's/<old>/<new>/g'
OS X: grep -r -l <old> * | xargs sed -i '' 's/<old>/<new>/g'
For grep:
-r recursively searches subdirectories
-l prints file names that contain matches
For sed:
-i extension (Note: An argument needs to be provided on OS X)
Those commands won't work in the default sed that comes with Mac OS X.
From man 1 sed:
-i extension
Edit files in-place, saving backups with the specified
extension. If a zero-length extension is given, no backup
will be saved. It is not recommended to give a zero-length
extension when in-place editing files, as you risk corruption
or partial content in situations where disk space is exhausted, etc.
Tried
sed -i '.bak' 's/old/new/g' logfile*
and
for i in logfile*; do sed -i '.bak' 's/old/new/g' $i; done
Both work fine.
#PaulR posted this as a comment, but people should view it as an answer (and this answer works best for my needs):
sed -i 's/abc/xyz/g' xa*
This will work for a moderate amount of files, probably on the order of tens, but probably not on the order of millions.
Another more versatile way is to use find:
sed -i 's/asd/dsg/g' $(find . -type f -name 'xa*')
I'm using find for similar task. It is quite simple: you have to pass it as an argument for sed like this:
sed -i 's/EXPRESSION/REPLACEMENT/g' `find -name "FILE.REGEX"`
This way you don't have to write complex loops, and it is simple to see, which files you are going to change, just run find before you run sed.
u can make
'xxxx' text u search and will replace it with 'yyyy'
grep -Rn '**xxxx**' /path | awk -F: '{print $1}' | xargs sed -i 's/**xxxx**/**yyyy**/'
There's some good answers above. I thought I'd throw in one more that is succinct and parallelizable, using GNU parallel, which I often prefer to xargs:
parallel sed -i 's/abc/xyz/g' {} ::: xa*
Combine this with the -j N option to run N jobs in parallel.
If you are able to run a script, here is what I did for a similar situation:
Using a dictionary/hashMap (associative array) and variables for the sed command, we can loop through the array to replace several strings. Including a wildcard in the name_pattern will allow to replace in-place in files with a pattern (this could be something like name_pattern='File*.txt' ) in a specific directory (source_dir).
All the changes are written in the logfile in the destin_dir
#!/bin/bash
source_dir=source_path
destin_dir=destin_path
logfile='sedOutput.txt'
name_pattern='File.txt'
echo "--Begin $(date)--" | tee -a $destin_dir/$logfile
echo "Source_DIR=$source_dir destin_DIR=$destin_dir "
declare -A pairs=(
['WHAT1']='FOR1'
['OTHER_string_to replace']='string replaced'
)
for i in "${!pairs[#]}"; do
j=${pairs[$i]}
echo "[$i]=$j"
replace_what=$i
replace_for=$j
echo " "
echo "Replace: $replace_what for: $replace_for"
find $source_dir -name $name_pattern | xargs sed -i "s/$replace_what/$replace_for/g"
find $source_dir -name $name_pattern | xargs -I{} grep -n "$replace_for" {} /dev/null | tee -a $destin_dir/$logfile
done
echo " "
echo "----End $(date)---" | tee -a $destin_dir/$logfile
First, the pairs array is declared, each pair is a replacement string, then WHAT1 will be replaced for FOR1 and OTHER_string_to replace will be replaced for string replaced in the file File.txt. In the loop the array is read, the first member of the pair is retrieved as replace_what=$i and the second as replace_for=$j. The find command searches in the directory the filename (that may contain a wildcard) and the sed -i command replaces in the same file(s) what was previously defined. Finally I added a grep redirected to the logfile to log the changes made in the file(s).
This worked for me in GNU Bash 4.3 sed 4.2.2 and based upon VasyaNovikov's answer for Loop over tuples in bash.
The Silver Searcher Solution
I'm adding another option for those people who don't know about the amazing tool called The Silver Searcher (command line tool is ag).
Note: You can use grep and other tools to do the same thing here, but The Silver Searcher is fantastic :)
TLDR
ag -l 'abc' | xargs sed -i 's/abc/xyz/g'
Install The Silver Searcher
sudo apt install silversearcher-ag # Debian / Ubuntu
sudo pacman -S the_silver_searcher # Arch / EndeavourOS
sudo yum install epel-release the_silver_searcher # RHEL / CentOS
Demo Files
Paste the following into your terminal to create some demonstration files:
mkdir /tmp/food
cd /tmp/food
content="Everybody loves to abc this food!"
echo "$content" > ./milk
echo "$content" > ./bread
mkdir ./fastfood
echo "$content" > ./fastfood/pizza
echo "$content" > ./fastfood/burger
mkdir ./fruit
echo "$content" > ./fruit/apple
echo "$content" > ./fruit/apricot
Using 'ag'
The following ag command will recursively find all the files that contain the string 'abc'. It ignores the .git directory, .gitignore files, and other ignore files:
$ ag 'abc'
milk
1:Everybody loves to abc this food!
bread
1:Everybody loves to abc this food!
fastfood/burger
1:Everybody loves to abc this food!
fastfood/pizza
1:Everybody loves to abc this food!
fruit/apple
1:Everybody loves to abc this food!
fruit/apricot
1:Everybody loves to abc this food!
To just list the files that contain the string 'abc', use the -l switch:
$ ag -l 'abc'
bread
fastfood/burger
fastfood/pizza
fruit/apricot
milk
fruit/apple
Changing Multiple Files
Finally, using xargs and sed, we can replace the 'abc' string with another string:
ag -l 'abc' | xargs sed -i 's/abc/eat/g'
In the above command, ag is listing all the files that contain the string 'abc'. The xargs command is splitting the file names and piping them individually into the sed command.
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I want to use cron job, that once per three day will clean and sort maillog.
My job looks like
/bin/sed -i /status=/!d /var/log/maillog |
(/bin/grep "status=bounced" /var/log/maillog | /bin/grep -E -o --color "\b[a-zA-Z0-9.-]+#[a-zA-Z0-9.-]+\.[a-zA-Z0-9.-]+\b" | /bin/sort -u >> /root/unsent.log) |
(/bin/grep "status=deferred" /var/log/maillog | /bin/grep -E -o --color "\b[a-zA-Z0-9.-]+#[a-zA-Z0-9.-]+\.[a-zA-Z0-9.-]+\b" | /bin/sort -u >> /root/deferred.log) |
(/bin/grep "status=sent" /var/log/maillog | /bin/grep -E -o --color "\b[a-zA-Z0-9.-]+#[a-zA-Z0-9.-]+\.[a-zA-Z0-9.-]+\b" | /bin/sort -u >> /root/sent.log) |
/bin/sed -i "/status=/d" /var/log/maillog
Job works fine and do 3 step:
Delete from maillog all lines that don't contain "status="
Sort sent, bounced, deffered in different logs.
Delete from maillog all lines that contain "status"
After this job my maillog is fully clean and sorted to 3 logs.
But Postfix doesn't want to write next records to maillog.
I delete sed command, and Postfix writes next records fine.
Why sed command blocks maillog after execution cron job?
sed -i will unlink the file it modifies, so syslog/postfix will continue writing to a nonexistent file.
From http://en.wikipedia.org/wiki/Sed:
Note: "sed -i" overwrites the original file with a new one, breaking any links the original may have had
It is more common to process log files after rotating them out of place with a tool like logrotate or savelog, so that syslog can continue writing uninterrupted.
If you must edit /var/log/maillog in place, you can add a line to the end of your cron job to reload syslog when you are done. Note that you can lose log lines written to the file while your script is running if you do this. The command will depend on what distribution / operating system you are running. On ubuntu, which uses rsyslog, it would be reload rsyslog >/dev/null 2>&1.
I've reformatted your original code to highlight the pipe-lines you added
/bin/sed -i /status=/!d /var/log/maillog \
| (/bin/grep "status=bounced" /var/log/maillog \
| /bin/grep -E -o --color "\b[a-zA-Z0-9.-]+#[a-zA-Z0-9.-]+\.[a-zA-Z0-9.-]+\b" \
| /bin/sort -u >> /root/unsent.log\
) \
| (/bin/grep "status=deferred" /var/log/maillog \
| /bin/grep -E -o --color "\b[a-zA-Z0-9.-]+#[a-zA-Z0-9.-]+\.[a-zA-Z0-9.-]+\b" \
| /bin/sort -u >> /root/deferred.log\
) \
| (/bin/grep "status=sent" /var/log/maillog \
| /bin/grep -E -o --color "\b[a-zA-Z0-9.-]+#[a-zA-Z0-9.-]+\.[a-zA-Z0-9.-]+\b" \
| /bin/sort -u >> /root/sent.log \
) \
| /bin/sed -i "/status=/d" /var/log/maillog
As #alberge noted, you could very likely lose log messages with all of this sed -i processing on the same file.
I propose a different approach:
I would move the maillog to a dated filename, (the assumption here is that Postfix, will create a new file with the standard name that it 'likes' to use (/var/log/maillog).
Then your real goal seems to be to extract various categories of messages to separately named files, i.e. unsent.log, deferred.log, sent.log AND then you're discarding any lines that don't contain the string status= (although you do that first).
Here's my alternate (please read the whole message, don't copy/paste/excute right away!).
logDate=$(/bin/date +%Y%m%d.%H%M%S)
/bin/mv /var/log/maillog /var/log/maillog.${logDate}
/bin/grep "status=bounced" /var/log/maillog.${logDate} \
| /bin/grep -E -o --color "\b[a-zA-Z0-9.-]+#[a-zA-Z0-9.-]+\.[a-zA-Z0-9.-]+\b" \
| /bin/sort -u \
>> /root/unsent.log.${logDate}
/bin/grep "status=deferred" /var/log/maillog.${logDate} \
| /bin/grep -E -o --color "\b[a-zA-Z0-9.-]+#[a-zA-Z0-9.-]+\.[a-zA-Z0-9.-]+\b" \
| /bin/sort -u \
>> /root/deferred.log.${logDate}
/bin/grep "status=sent" \
| /bin/grep -E -o --color "\b[a-zA-Z0-9.-]+#[a-zA-Z0-9.-]+\.[a-zA-Z0-9.-]+\b" \
| /bin/sort -u \
>> /root/sent.log.${logDate}
To test that this code is working, replace the 2nd line ( /bin/mv .... ) with
/bin/cp /var/log/maillog /var/log/maillog.${logDate}
Copy/paste that into a terminal window, confirm that the /var/log/maillog.${logDate} was copied correctly, then copy/paste each section, 1 at a time and check that the expected output is created in each of the /root logfiles.
(If you get error messages for any of these blocks, make sure there are NO space/tab chars after the last '\' char on each of the continued lines. OR you can fold each of those 3 pipelines back into one line, removing the '\' chars as you go.
(Note that to create each of the /root logfiles, I don't use any connecting sections via pipes surrounded by sub-processes. But, in other situations, I do use this sort of technique for advanced problems, so don't throw the technique away, just use it when it is really required ;-)!
After you confirm that all of this is working as you needed, then you extend the script to do a final cleaning up :
/bin/rm /var/log/maillog.${logDate}
I've added ${logDate} to each of your output files, but as I see you're using sort -u >> you may want to remove that 'extension' to your sub-logfile names (unsent.log, deferred.log, sent.log) And just let those files get grow naturally. In either case, you'll have to comeback at some point and determine how far back you want to keep this data, and develop a plan and method for how you'll clean up these logfiles when they're not useful. I think someone mentioned logrotate package. You might want to look into that as your long-term solution.
This solution avoids a lot of extra processes being created, and it eliminates (mostly) the possibility of lost log records. I'm think you might lose all or part of a record if Postfix is writing to the logfile in the same split-second as you are moving the file. But your solution would have similar problems AND more opportunities for that to happen.
If I have misunderstood the intention of your design, using the nested ( .... ) | ( .... ) sub-processes, sorry! Consider updating your post to include why you are using that techinque.
I hope this helps.