I'm using a sed command for replacing some words in text files. This command is embedded in a ksh script.
I would like to reach that not everytime will every replacement rule of sed fire, only if some conditions are filled. E.g. depending on a value of a shell variable.
In other words I would like to write this script without the if statement, I would rather include the conditional expression inside the sed. Is it possible?
REPLACE_A=TRUE
if [ "$REPLACE_A" = "TRUE" ]
then
cat myfile \
| sed 's/A/B/g;
's/C/D/g;
's/E/F/g;'
else
cat myfile \
| sed 's/C/D/g;
's/E/F/g;'
fi
The only solution that pops into my mind is to store the sed command in a variable, like
# in your script
SEDCMD=""
# ...
SEDCMD="s/A/B/g;"
# later
SEDCMD="${SEDCMD}s/C/D/g;"
# ...
# finally
sed "$SEDCMD" FILE
But it still not the solution you want.
You can't do it with sed, but with awk. If you like to try, I suggest you have a look at this:
http://www.grymoire.com/Unix/Awk.html
Related
I have a shell script that contains the following line
PROC_ID=$(cat myfile.sh | grep running)
which, after you echo out the value would be 1234 or something like that.
What I want to do is find and replace instances of this line with a literal value
I want to replace it with PROC_ID=1234 instead of having the function call.
I've tried doing this in another shell script using sed but I can't get it to work
STR_TO_USE="PROC_ID=${1}"
STR_TO_REP='PROC_ID=$(cat myfile.sh | grep running)'
sed -i "s/$STR_TO_REP/$STR_TO_USE/g" sample.sh
but it complains stating sed: 1: "sample.sh": unterminated substitute pattern
How can I achieve this?
EDIT:
sample.sh should contain beforehand
#!/bin/bash
....
PROC_ID=$(cat myfile.sh | grep running)
echo $PROC_ID
....
After, it should contain
#!/bin/bash
....
PROC_ID=1234
echo $PROC_ID
....
The script I'm using as described above will be taking the in an arg from the command line, hence STR_TO_USE="PROC_ID=${1}"
Simply:
sed /^PROC_ID=/s/=.*/=1234/
Translation:
At line begining by PROC_ID=
replace = to end of line by =1234.
or more accurate
sed '/^[ \o11]*PROC_ID=.*myfile.*running/s/=.*/=1234/'
could be enough
([ \o11]* mean some spaces and or tabs could even prepand)
Well, first, I want to point out something obvious. This: $(cat myfile.sh | grep running) will at the very least NOT only contain the string 1234 but will certainly also contain the string running. But since you aren't asking for help with that, I'll leave it alone.
All you need in your above sed, is first to backslash the $.
STR_TO_REP='PROC_ID=\$(cat myfile.sh | grep running)'
This allows the sed command to be terminated.
File info has some certain info on a line starting with myline. Im trying to pass it to a script like this:
bash myscript `cat info | grep myline`
This works well. Script gets "myline" as first argument. But now i want to add a "w" at the end of that. I tried
bash myscript `cat info | grep myline`w
This is already problematic, the script gets "wyline" as first argument.
And now the next step is that i actually want to have an if statement whether i want to add w or not. Tried this:
bash myscript `cat info | grep myline``[ "condition" == "condition"] && echo "w"`
This works the same way. Script gets "wyline" as first argument.
So I have two questions:
1) How to fix the "wyline" result to get desired "mylinew"
2) Is there a better way to write this if statement after cat?
Do not use backticks `, use $(...) instead. bash hackers obsolete deprecated syntax
cat file | grep is a useless use of cat useless use of cat award. Just grep file.
Just quote the result and add w:
myscript "$(grep myline info)w"
You can add a trailing w to the last line of input with sed:
myscript "$(grep myline info | sed '$s/$/w/')"
I would advise to always quote your variable expansions.
Script gets "wyline" as first argument.
Your input file has dos line endings. Inspect output with cut -v or hexdump -C or xxd. Use dos2unix and remove carriage return characters.
Okay, I am a newbie to Unix scripting. I was given the task to find a temporary work around for this:
cat /directory/filename1.xml |sed -e "s/ABCXYZ/${c}/g" > /directory/filename2.xml
$c is a variable from a sqlplus count query. I totally understand how this sed command is working. But here is where I am stuck. I am storing the count associated with the variable in another file called filename3 as count[$c] where $c is replaced with a number. So my question is how can I update this sed command to substitute ABCXYZ with the count from file3?
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
UPDATE: In case anyone has a similar issue I got mine to work using:
rm /directory/folder/variablefilename.dat
echo $c >> /directory/folder/variablefilename.dat
d=$(grep [0-9] /directory/folder/variablefilename.dat)
sed -3 "s/ABC123/${d}/g" /directory/folder/inputfile.xml >> /directory/folder/outputfile.xml
thank you to Kaz for pointing me in the right direction
Store the count in filename3 using the syntax c=number. Then you can source the file as a shell script:
. /filename3 # get c variable
sed -e "s/ABCXYZ/${c}/g" /directory/filename1.xml > /directory/filename2.xml
If you can't change the format of filename3, you can write a shell function which scrapes the number out of that file and sets the c variable. Or you can scrape the number out with an external program like grep, and then interpolate its output into a variable assignment using command substitution: $(command arg ...) syntax.
Suppose we can rely on file3 to contain exactly one line of the form count[42]. Then we can just extract the digits with grep -o:
c=$(grep -E -o '[0-9]+' filename3)
sed -e "s/ABCXYZ/$c/g" /directory/filename1.xml > /directory/filename2.xml
The c variable can be eliminated, of course; you can stick the $(grep ...) into the sed command line in place of $c.
A file which contains numerous instances of syntax like count[42] for various variables could be transformed into a set of shell variable assignments using sed, and then sourced into the current shell to make those assignments happen:
$ sed -n -e 's/^\([A-Za-z_][A-Za-z0-9_]\+\)\[\(.*\)\]/\1=\2/p' filename3 > vars.sh
$ . ./vars.sh
you can use sed like this
sed -r "s/ABCXYZ/$(sed -nr 's/.*count[[]([0-9])+[]].*/\1/p' path_to_file)/g" path_to_file
the expression is double quoted which allow the shell to execute below and find the number in count[$c] in the file and use it as a substitute
$(sed -nr 's/.*count[[]([0-9])+[]].*/\1/p' path_to_file)
Using bash, how would one replace all unquoted characters from a file?
I have a system that I can't modify that spits out CSV files such as:
code;prop1;prop2;prop3;prop4;prop5;prop6
0,1000,89,"a1,a2,a3",33,,
1,,,"a55,a10",1,1 L,87
2,25,1001,a4,,"1,5 L",
I need this to become, for a new system being added
code;prop1;prop2;prop3;prop4;prop5;prop6
0;1000;89;a1,a2,a3;33;;
1;;;a55,a10;1;1 L;87
2;25;1001;a4;1,5 L;
If the quotes can be removed after this substitution happens in one command it would be nice :) But I prefer clarity to complicated one-liners for future maintenance.
Thank you
With sed:
sed -e 's/,/;/g' -e ':loop; s/\("\)\([^;]*\);\([^"]*"\)/\1\2,\3/; t loop'
Test:
$ sed -e 's/,/;/g' -e ':loop; s/\("\)\([^;]*\);\([^"]*"\)/\1\2,\3/; t loop' yourfile
code;prop1;prop2;prop3;prop4;prop5;prop6
0;1000;89;"a1,a2,a3";33;;
1;;;"a55,a10";1;1 L;87
2;25;1001;a4;;"1,5 L";
You want to use a csv parser. Parsing csv with shell tools is hard (you will encounter regular expressions soon, and they rarely get all cases).
There is one in almost every language. I recommend python.
You can also do this using excel/openoffice variants by opening the file and then saving with ; as the separator.
You can used sed:
echo '0,1000,89,"a1,a2,a3",33,,' | sed -e "s|\"||g"
This will replace " with the empty string (deletes it), and you can pipe another sed to replace the , with ;:
sed -e "s|,|;|g"
$ echo '0,1000,89,"a1,a2,a3",33,,' | sed -e "s|\"||g" | sed -e "s|,|;|g"
>> 0;1000;89;a1;a2;a3;33;;
Note that you can use any separator you want instead of | inside the sed command. For example, you can rewrite the first sed as:
sed -e "s-\"--g"
Basically I want to copy several lines of code from a template file to a script file.
Is it even possible to use sed to copy a string full of symbols that interact with the script?
I used these lines:
$SWAP='sudo cat /home/kaarel/template'
sed -i -e "s/#pointer/${SWAP}/" "script.sh"
The output is:
./line-adder.sh: line 11: =sudo cat /home/kaarel/template: No such file or directory
No, it is not possible to do this robustly with sed. Just use awk:
awk -v swap="$SWAP" '{sub(/#pointer/,swap)}1' script.sh > tmp && mv tmp script.sh
With recent versions of GNU awk there's a -i inplace flag for inplace editing if that's something you care about.
Good point about "&&". Here's the REALLY robust version that will work for absolutely any character in the search or replacement strings:
awk -v old="#pointer" -v new="$SWAP" 's=index($0,old){$0 = substr($0,1,s-1) new substr($0,s+length(old))} 1'
e.g.:
$ echo "abc" | awk -v old="b" -v new="m&&n" 's=index($0,old){$0 = substr($0,1,s-1) new substr($0,s+length(old))} 1'
am&&nc
There are two issues with the line:
$SWAP='sudo cat /home/kaarel/template'
The first is that, before executing the line, bash performs variable expansion and replaces $SWAP with the current value of SWAP. That is not what you wanted. You wanted bash to assign a value to SWAP.
The second issue is that the right-hand side is enclosed in single-quotes which protect the string from expansion. You didn't want to protect the string from expansion: you wanted to execute it. To execute it, you can use back-quotes which may look similar but act very differently.
Back-quotes, however, are an ancient form of asking for command execution. The more modern form is $(...) which eliminates some problems that back-quotes had.
Putting it all together, use:
SWAP=$(sudo cat /home/kaarel/template)
sed -i -e "s/#pointer/${SWAP}/" "script.sh"
Be aware, though, that the sed command may have problems if there are any sed-active characters in the template file.