I want to replace the date found at the end of the "datadir" line with the current date.
For e.g. my my.cnf file looks like this...
# head /etc/my.cnf
[mysqld]
#mount -t tmpfs -o size=102m tmpfs /mnt
#datadir=/mnt
read-only
datadir=/mysqlApr5
#datadir=/mysqlApr2
#datadir=/mysqlMar16
#datadir=/mysqlFeb25a
Most of the lines are commented. I need to find the datadir line that is not commented and then replace the /mysqlApr4 with /mysqlApr20
datadir=/mysqlApr20
If it is possible I will like to comment the older datadir path.
#datadir=/mysqlApr5
I can output the current date as:
date '+%b%d'
But I want to concat it with the word "/mysql" and replace or comment the current datadir line.
You can do it with sed and an in-place replacement:
sed -i "s|^datadir=.*$|datadir=/mysql`date '+%b%d'`|" /etc/my.cnf
If you want to comment out the old line and add a new one, you can use sed to do the commenting and just append a new line:
sed -i "s|^datadir=.*$|#\\0|" /etc/my.cnf
echo "datadir=/mysql`date '+%b%d'`" >> /etc/my.cnf
Perl one-liner which edits the file in-place:
perl -i -nle 'BEGIN { $date = `date +%b%d` }; if (/^datadir=/) { print qq{#$_\ndatadir=/mysql$date} } else {print}' my.cnf
awk -vd="$(date +%b%d)" '!/#/&&/datadir/{$0="#"$0"\ndatadir=/mysql"d}1' /etc/my.cnf>temp && mv temp file
All in one fell swoop:
sed -i '/^datadir.*/{s.^.#.;s.$.\ndatadir=/mysql'$(date "+%b%d")'.;q}' /etc/my.cnf
This will comment out the uncommented line. It adds the new line immediately below the old one instead of at the end of the file so it works similarly to the AWK and Perl versions shown.
Related
I'm trying to add the filename of a text file into the first line of a the same text file. for example if the file name is called test1.txt, then the first line when you open the file should be test1.
below is what I've done so for, the only problem i have is that the word "$file" is being written to the file not the file name. any help is appreciated.
for file in *.txt; do
sed -i '1 i\$file' $file;
awk 'sub("$", "\r")' "$file" > "$file"1;
mv "$file"1 "$file";
done
Without concise, testable sample input and expected output it's an untested guess but it SOUNDS like all you need is:
awk -i inplace -v ORS='\r\n' 'FNR==1{print FILENAME}1' *
No shell loop or multiple commands required.
The above uses GNU awk for inplace editing and I'm assuming the sub() in your code was intended to add a \r at the end of every line.
I've just started learning more about sed and awk and put this into a file called insert.sed and sourced it and passed it a file name:
sed -i '1s/^./'$1'\'$'\n/g' $1
In trying it, it seems to work okay:
rent$ cat x.txt
<<< Who are you?
rent$ source insert.sed x.txt
rent$ cat x.txt
x.txt
<< Who are you?
It is cutting off the first character of the first line so I'd have to fix that otherwise it does add the file name to first line.
I'm sure there's better ways of doing it.
If you want test1 on first line, with gnu sed
sed -i '1{x;s/.*/fich=$(ps -p $PPID -o args=);fich=${fich##*\\} };echo ${fich%%.*}/e;G}' test1.txt
I have a text file with 4 columns delimited by comma.
As I am reading each record in a loop, I want to add a value to the 5th column depending on a condition.
So if I know the row number and column number, how can I use awk/sed commands to replace/set value at that particular field without using temporary files?
I want to update the file (directly) that I am reading from
inp.txt
a,b,c,d
e,f,g,h
i,j,k,l
Thanks,
-sri
I can't speak for sed, but the purpose of awk isn't to edit files in place but to write to stdout.
But anyway, here's a solution you don't need a loop for, pretending the condition is that the entry in column 4 is an h.
awk -F ',' '{ if ($4 == "h") print $0",z"; else print $0","}' inp.txt > out.txt
output:
a,b,c,d,
e,f,g,h,z
i,j,k,l,
You cannot directly edit the file with either awk or sed. Some versions of sed have an option (-i) that works with a temporary file and overwrites the original file, but it does not actually edit the file in place. This is not a big deal. Just do:
$ awk 'NR==5{ $(NF+1) = "new value"}1' OFS=, FS=, input-file > tmp.$$
$ mv tmp.$$ input-file
To add a new column to row 5 of input-file. If you wish, you can use ed to edit the file, but it makes more sense to use a temporary file. If you want to pretend that you aren't using a temporary file, and your sed supports -i, you can do the same thing with:
sed -i '5s/$/,new value/' input-file
Even though most utilitites do not allow in-place modification of the file, it is simple to use one of the following sh functions to emulate that behavior using temporary files:
edit() { local f=$1; shift; "$#" < $f > $f.$$ && mv $f.$$ $f; } # Break hard links
edit() { local f=$1; shift; "$#" < $f > $f.$$ && cat $f.$$ > $f && rm $f.$$; }
With either of these, you could use awk to give the appearance of editing files in-place using edit filename awk awk-cmds. The first version breaks hard links, but uses slightly less IO.
perl -i -F, -lane 'if($.==<row number>){$F[<column_number>-1]+=<add your stuff here>}print join(",",#F)' your_file
tested below:
>cat temp
b,c,d,g
r,g,d,s
execute for changing the 3rd column in second row:
>perl -i -F, -lane 'if($.==2){$F[2]=10}print join(",",#F)' temp
> cat temp
b,c,d,g
r,g,10,s
You mean like this?
this is the version don't using any temporary files.
[a#b ~]$ cat tmp | sed 's_^\(.*\),\(.*\),\(.*\),\(.*\)_\1,\2,\3,\4_g'
inp.txt
a,b,c,d
e,f,g,h
i,j,k,l
[a#b ~]$ cat tmp | sed 's_^\(.*\),\(.*\),\(.*\),\(.*\)_\1,sth,\3,\4_g'
inp.txt
a,sth,c,d
e,sth,g,h
i,sth,k,l
[a#b ~]$ sed -ie 's_^\(.*\),\(.*\),\(.*\),\(.*\)_\1,sth,\3,\4_g' tmp
[a#b ~]$ cat tmp
inp.txt
a,sth,c,d
e,sth,g,h
i,sth,k,l
Cheers,
I have a CSV. I want to edit the 35th field of the CSV and write the change back to the 35th field. This is what I am doing on bash:
awk -F "," '{print $35}' test.csv | sed -i 's/^0/+91/g'
so, I am pulling the 35th entry using awk and then replacing the "0" in the starting position in the string with "+91". This one works perfet and I get desired output on the console.
Now I want this new entry to get written in the file. I am thinking of sed's "in -place" replacement feature but this fetuare needs and input file. In above command, I cannot provide input file because my primary command is awk and sed is taking the input from awk.
Thanks.
You should choose one of the two tools. As for sed, it can be done as follows:
sed -ri 's/^(([^,]*,){34})0([^,]*)/\1+91\3/' test.csv
Not sure about awk, but #shellter's comment might help with that.
The in-place feature of sed is misnamed, as it does not edit the file in place. Instead, it creates a new file with the same name. eg:
$ echo foo > foo
$ ln -f foo bar
$ ls -i foo bar # These are the same file
797325 bar 797325 foo
$ echo new-text > foo # Changes bar
$ cat bar
new-text
$ printf '/new/s//newer\nw\nq\n' | ed foo # Edit foo "in-place"; changes bar
9
newer-text
11
$ cat bar
newer-text
$ ls -i foo bar # Still the same file
797325 bar 797325 foo
$ sed -i s/new/newer/ foo # Does not edit in-place; creates a new file
$ ls -i foo bar
797325 bar 792722 foo
Since sed is not actually editing the file in place, but writing a new file and then renaming it to the old file, you might as well do the same.
awk ... test.csv | sed ... > test.csv.1 && mv test.csv.1 test.csv
There is the misperception that using sed -i somehow avoids the creation of the temporary file. It does not. It just hides the fact from you. Sometimes abstraction is a good thing, but other times it is unnecessary obfuscation. In the case of sed -i, it is the latter. The shell is really good at file manipulation. Use it as intended. If you do need to edit a file in place, don't use the streaming version of ed; just use ed
So, it turned out there are numerous ways to do it. I got it working with sed as below:
sed -i 's/0\([0-9]\{10\}\)/\+91\1/g' test.csv
But this is little tricky as it will edit any entry which matches the criteria. however in my case, It is working fine.
Similar implementation of above logic in perl:
perl -p -i -e 's/\b0(\d{10})\b/\+91$1/g;' test.csv
Again, same caveat as mentioned above.
More precise way of doing it as shown by Lev Levitsky because it will operate specifically on the 35th field
sed -ri 's/^(([^,]*,){34})0([^,]*)/\1+91\3/g' test.csv
For more complex situations, I will have to consider using any of the csv modules of perl.
Thanks everyone for your time and input. I surely know more about sed/awk after reading your replies.
This might work for you:
sed -i 's/[^,]*/+91/35' test.csv
EDIT:
To replace the leading zero in the 35th field:
sed 'h;s/[^,]*/\n&/35;/\n0/!{x;b};s//+91/' test.csv
or more simply:
|sed 's/^\(\([^,]*,\)\{34\}\)0/\1+91/' test.csv
If you have moreutils installed, you can simply use the sponge tool:
awk -F "," '{print $35}' test.csv | sed -i 's/^0/+91/g' | sponge test.csv
sponge soaks up the input, closes the input pipe (stdin) and, only then, opens and writes to the test.csv file.
As of 2015, moreutils is available in package repositories of several major Linux distributions, such as Arch Linux, Debian and Ubuntu.
Another perl solution to edit the 35th field in-place:
perl -i -F, -lane '$F[34] =~ s/^0/+91/; print join ",",#F' test.csv
These command-line options are used:
-i edit the file in-place
-n loop around every line of the input file
-l removes newlines before processing, and adds them back in afterwards
-a autosplit mode – split input lines into the #F array. Defaults to splitting on whitespace.
-e execute the perl code
-F autosplit modifier, in this case splits on ,
#F is the array of words in each line, indexed starting with 0
$F[34] is the 35 element of the array
s/^0/+91/ does the substitution
My target is to delete line in file only if PATH match the PATH in the file
For example, I need to delete all lines that have /etc/sysconfig PATH from /tmp/file file
more /tmp/file
/etc/sysconfig/network-scripts/ifcfg-lo file1
/etc/sysconfig/network-scripts/ifcfg-lo file2
/etc/sysconfig/network-scripts/ifcfg-lo file3
I write the following Perl code (the perl code integrated in my bash script) in order to delete lines that have "/etc/sysconfig"
export FILE=/etc/sysconfig
perl -i -pe 's/\Q$ENV{FILE}\E// ' /tmp/file
But I get the following after I run the perl code: (in place to get empty lines)
/network-scripts/ifcfg-lo file1
/network-scripts/ifcfg-lo file2
/network-scripts/ifcfg-lo file3
first question:
How to change the perl syntax : perl -i -pe 's/\Q$ENV{FILE }\E// ' in order to delete line that matches the required PATH (/etc/sysconfig)?
second question:
The same as the first question but line will deleted only if PATH match the first field in the file
Example:
/tmp/file before perl edit:
file1 /etc/sysconfig/network-scripts/ifcfg-lo
/etc/sysconfig/network-scripts/ifcfg-lo file2
/etc/sysconfig/network-scripts/ifcfg-lo file3
/tmp/file after perl edit:
file1 /etc/sysconfig/network-scripts/ifcfg-lo
Perl is a fine way to do it. Use the -n switch, not -p.
perl -i -l -n -e'print unless /\Q$ENV{FILE}/' filename
s/pattern/otherpattern/ won't delete entire lines; it will only alter substrings. You need to entirely change your program to delete entire lines. In pseudocode, it would be:
while (read in a line)
{
if (doesn't match)
{
write the line back out unaltered.
}
}
It can still be rewritten as a oneliner though, with knowledge of how continue and redo work in loops: perl -pe '$_ = <> and redo if /Q$ENV{FILE}\E/'
mef#iwlappy:~$ cat /tmp/file
aaaa
/etc/sysconfig/network-scripts/ifcfg-lofile1
/etc/sysconfig/network-scripts/ifcfg-lofile2
/etc/sysconfig/network-scripts/ifcfg-lofile3
aaa
mef#iwlappy:~$ perl -i -pe 's/$ENV{FILE}\E.*//' /tmp/file
mef#iwlappy:~$ cat /tmp/file
aaaa
aaa
You can do a further regexp to remove empty lines with s/^$//
If I were doing this from the command line, I probably wouldn't even use Perl. I'd just use a negated grep:
$ mv old.txt old.bak; grep -v $FILE old.bak > old.txt
Renaming the original file and writing to a new file with the old name is the same thing that perl's -i switch does for you.
If you want to match just the first column, then I might punt to perl so I don't have to use awk or cut. perl's -a switch splits the line on whitespace and puts the results in #F:
$ perl -ai.bak -ne 'print if $F[0] !~ /^\Q$ENV{FILE}/' old.txt
When you think you have it right, you can remove the .bak training wheels that saves a copy of your original file. Or not. I tend to like the safety net.
See perlrun for the details of command-line switches.
I have a file that contains this kind of paths:
C:\bad\foo.c
C:\good\foo.c
C:\good\bar\foo.c
C:\good\bar\[variable subdir count]\foo.c
And I would like to get the following file:
C:\bad\foo.c
C:/good/foo.c
C:/good/bar/foo.c
C:/good/bar/[variable subdir count]/foo.c
Note that the non matching path should not be modified.
I know how to do this with sed for a fixed number of subdir, but a variable number is giving me trouble. Actually, I would have to use many s/x/y/ expressions (as many as the max depth... not very elegant).
May be with awk, but this kind of magic is beyond my skills.
FYI, I need this trick to correct some gcov binary files on a cygwin platform.
I am dealing with binary files; therefore, I might have the following kind of data:
bindata\bindata%bindataC:\good\foo.c
which should be translated as:
bindata\bindata%bindataC:/good/foo.c
The first \ must not be translated, despite that it is on the same line.
However, I have just checked my .gcno files while editing this text and it looks like all the paths are flanked with zeros, so most of the answers below should fit.
sed -e '/^C:\\good/ s/\\/\//g' input_file.txt
I would recommend you look into the cygpath utility, which converts path names from one format to another. For instance on my machine:
$ cygpath `pwd`
/home/jericson
$ cygpath -w `pwd`
D:\root\home\jericson
$ cygpath -m `pwd`
D:/root/home/jericson
Here's a Perl implementation of what you asked for:
$ echo 'C:\bad\foo.c
C:\good\foo.c
C:\good\bar\foo.c
C:\good\bar\[variable subdir count]\foo.c' | perl -pe 's|\\|/|g if /good/'
C:\bad\foo.c
C:/good/foo.c
C:/good/bar/foo.c
C:/good/bar/[variable subdir count]/foo.c
It works directly with the string, so it will work anywhere. You could combine it with cygpath, but it only works on machines that have that path:
perl -pe '$_ = `cygpath -m $_` if /good/'
(Since I don't have C:\good on my machine, I get output like C:goodfoo.c. If you use a real path on your machine, it ought to work correctly.)
You want to substitute '/' for all '\' but only on the lines that match the good directory path. Both sed and awk will let you do this by having a LHS (matching) expression that only picks the lines with the right path.
A trivial sed script to do this would look like:
/[Cc]:\\good/ s/\\/\//g
For a file:
c:\bad\foo
c:\bad\foo\bar
c:\good\foo
c:\good\foo\bar
You will get the output below:
c:\bad\foo
c:\bad\foo\bar
c:/good/foo
c:/good/foo/bar
Here's how I would do it in awk:
# fixpaths.awk
/C:\\good/ {
gsub(/\\/,"/",$1);
print $1 >> outfile;
}
Then run it using the command:
awk -f fixpaths.awk paths.txt; mv outfile paths.txt
Or with some help from good ol' Bash:
#!/bin/bash
cat file | while read LINE
do
if <bad_condition>
then
echo "$LINE" >> newfile
else
echo "$LINE" | sed -e "s/\\/\//g" >> newfile
fi
done
try this
sed -re '/\\good\\/ s/\\/\//g' temp.txt
or this
awk -F"\\" '{if($2=="good"){OFS="\/"; $1=$1;} print $0}' temp.txt