I have a javascript file with a jquery function call:
$.getScript('/scripts/files/file.js');
I want to replace that line with the contents of the file at that path. This is the bash script I have so far:
cat public/scripts/old.js | sed -e "s/$\.getScript\('(.)+'\);/$(cat \1)/g" > public/scripts/new.js
However, my regular expression and remembering the path does not seem to be working correctly. I get cat: 1: No such file or directory
as it seems as if cat is being called on the number 1 (which should be the remembered portion of the regexp). How can I fix this?
Because you are using $() inside double quotes, the shell is parsing the cat \1, stripping the backslash and trying to run cat 1 to pass its output as part of the argument to sed. Sed has a command (r) for reading a file, but the filename must be literal, and cannot be the result of previous sed commands (at least in standard sed, perhaps some implementations provide that ability). sed is really the wrong tool for this. You could do an awk solution, but it will be fragile.
Here's a possible perl solution (warning: fragile):
perl -ne 'if( $_ =~ /\$\.getScript\('"'(.*)'"'\)/ )
{ system( "cat $1" ) } else {print}' public/scripts/old.js
Related
I am doing perl -pe along with grep to do a multi line grep. This is being done so that when "" is used as a line continuation letter, I need to join the line.
So my file is
record -field X \
-field Y
I am doing
perl -pe 's/\\\n/ /' a/b/c/*/records/*.rec | grep "\-field.*X.*\-field.*Y"
The problem with this is that it just gives me the grep result, without telling me which file had the issue. Is there a way around this. I need to know which files have this too.
I can do a foreach shell script, but was wondering if there is a one liner version of the same possibe
Once you are inside a Perl program why go to system's grep? Perl's tools are far more abundant, rounded, and usable than the shell's. One way
perl -0777 -nE'say "$ARGV: $_" for
grep { /\-field.*X.*\-field.*Y/ } split /\n/, s{\\\n}{ }gr' file-list
(broken into lines for readability)
We read the whole file into $_ ("slurp" it), so to be able to merge those particular lines, using the -0777 switch. That \\n is then substituted with a space and the resulting string returned (by virtue of the /r modifier), and split by \n to regenerate lines.
Then that list of lines is fed to grep with your desired pattern, and the ones that match the pattern are passed through. So then they are printed, prepended with the name of the currently processed file, available in the $ARGV variable.
The answer is to use ARGV[0]
perl -pe 'print "$ARGV[0]: ";s/\\\n/ /' a/b/c/*/records/*.rec | grep "\-field.*X.*\-field.*Y"
I want to copy regex matched text to a new file.
<SHOPITEM>([\s\S]*?)<YEAR>2015<\/YEAR>([\s\S]*?)<\/SHOPITEM>
([\s\S]*?) = any text, any line
This works (I am able to find) in Sublime editor, but how this regex looks for sed/grep (or any other Unix tool)?
Usually sed and grep are used to search on lines not on multiline mode as is it still possible under certain conditions.
I would advise to use Perl which should be installed on your computer:
perl -p -e 'undef $/;$_=<>;print $& if /<SHOPITEM>([\s\S]*?)<YEAR>2015<\/YEAR>([\s\S]*?)<\/SHOPITEM>/i;'
Be aware that this regex won't work if you have nested <shopitem> tags or even multiple occurences. Instead use a XML parser.
Also you can write a Program that parse your xml file and this time it will capture all the matches.
myparser.pl:
#!/usr/bin/env perl
undef $/;
$_ = <>;
print while(/<(shopitem)>[\s\S]*<(year)>2015<\/\2>[\s\S]*<\/\1>/ig);
That you can execute:
$ chmod u+x myparser.pl
$ ./myparser.pl myfile.xml
I'm not the best scripter, but I think this should work:
grep "<SHOPITEM>" infile | grep "<YEAR>2015" | sed -e "s/<[^>]*>//g" | sed "s/2015/ /g" > outfile
Edit: I didn't match the regex, instead I got SHOPITEMs with YEAR 2015 tag and removed all the unwanted parts.
Edit: I'd do it this way, but I'm not sure it's the most elegant solution.
I'm not use to using grep on linux via the terminal. I'm use to using dnGREP on windows but there is no comparable gui tool on ubuntu from what I've found.
How do I match the regular expressions "^(.*?)[" with all files in a folder and replace it with a blankspace?
I assume this one would follow the same methodology "](?=[^.]*$)"
Also, how do I replace the text below to add new lines
{"dev_is_looking_week"
with the same text and 4 blank lines underneath. Ignore the "." at the end. StackOverflow won't show blank newlines without a character at the end.
{"dev_is_looking_week"
.
You are using the wrong tool. grep is for selecting data. You may want to use awk, perl or sed instead.
Some examples:
awk '/example/ {print; print "\n\n\n\n"; }'
awk '{print;} /example/ {print "\n\n\n\n"; }'
perl -ne 'print $_; /example/ && print "\n\n\n\n"'
Note that perl also has the neat -i option, for inplace modification of files, which comes in handy when you have to do this change on a lot of files.
Or you might opt for regexxer, redet, or kregexpeditor from KDE.
You can use sed like this:
sed 's/{"dev_is_looking_week"/&\n\n\n\n/' file
OR using awk:
awk '/{"dev_is_looking_week"/{$0=sprintf("%s\n\n\n\n", $0)} 1'
sed "s/\(.*\)/\t\1/" $filename > $sedTmpFile && mv $sedTmpFile $filename
I am expecting this sed script to insert a tab in front of every line in $filename however it is not. For some reason it is inserting a t instead.
Not all versions of sed understand \t. Just insert a literal tab instead (press Ctrl-V then Tab).
Using Bash you may insert a TAB character programmatically like so:
TAB=$'\t'
echo 'line' | sed "s/.*/${TAB}&/g"
echo 'line' | sed 's/.*/'"${TAB}"'&/g' # use of Bash string concatenation
#sedit was on the right path, but it's a bit awkward to define a variable.
Solution (bash specific)
The way to do this in bash is to put a dollar sign in front of your single quoted string.
$ echo -e '1\n2\n3'
1
2
3
$ echo -e '1\n2\n3' | sed 's/.*/\t&/g'
t1
t2
t3
$ echo -e '1\n2\n3' | sed $'s/.*/\t&/g'
1
2
3
If your string needs to include variable expansion, you can put quoted strings together like so:
$ timestamp=$(date +%s)
$ echo -e '1\n2\n3' | sed "s/.*/$timestamp"$'\t&/g'
1491237958 1
1491237958 2
1491237958 3
Explanation
In bash $'string' causes "ANSI-C expansion". And that is what most of us expect when we use things like \t, \r, \n, etc. From: https://www.gnu.org/software/bash/manual/html_node/ANSI_002dC-Quoting.html#ANSI_002dC-Quoting
Words of the form $'string' are treated specially. The word expands
to string, with backslash-escaped characters replaced as specified by
the ANSI C standard. Backslash escape sequences, if present, are
decoded...
The expanded result is single-quoted, as if the dollar sign had not
been present.
Solution (if you must avoid bash)
I personally think most efforts to avoid bash are silly because avoiding bashisms does NOT* make your code portable. (Your code will be less brittle if you shebang it to bash -eu than if you try to avoid bash and use sh [unless you are an absolute POSIX ninja].) But rather than have a religious argument about that, I'll just give you the BEST* answer.
$ echo -e '1\n2\n3' | sed "s/.*/$(printf '\t')&/g"
1
2
3
* BEST answer? Yes, because one example of what most anti-bash shell scripters would do wrong in their code is use echo '\t' as in #robrecord's answer. That will work for GNU echo, but not BSD echo. That is explained by The Open Group at http://pubs.opengroup.org/onlinepubs/9699919799/utilities/echo.html#tag_20_37_16 And this is an example of why trying to avoid bashisms usually fail.
I've used something like this with a Bash shell on Ubuntu 12.04 (LTS):
To append a new line with tab,second when first is matched:
sed -i '/first/a \\t second' filename
To replace first with tab,second:
sed -i 's/first/\\t second/g' filename
Use $(echo '\t'). You'll need quotes around the pattern.
Eg. To remove a tab:
sed "s/$(echo '\t')//"
You don't need to use sed to do a substitution when in actual fact, you just want to insert a tab in front of the line. Substitution for this case is an expensive operation as compared to just printing it out, especially when you are working with big files. Its easier to read too as its not regex.
eg using awk
awk '{print "\t"$0}' $filename > temp && mv temp $filename
I used this on Mac:
sed -i '' $'$i\\\n\\\thello\n' filename
Used this link for reference
sed doesn't support \t, nor other escape sequences like \n for that matter. The only way I've found to do it was to actually insert the tab character in the script using sed.
That said, you may want to consider using Perl or Python. Here's a short Python script I wrote that I use for all stream regex'ing:
#!/usr/bin/env python
import sys
import re
def main(args):
if len(args) < 2:
print >> sys.stderr, 'Usage: <search-pattern> <replace-expr>'
raise SystemExit
p = re.compile(args[0], re.MULTILINE | re.DOTALL)
s = sys.stdin.read()
print p.sub(args[1], s),
if __name__ == '__main__':
main(sys.argv[1:])
Instead of BSD sed, i use perl:
ct#MBA45:~$ python -c "print('\t\t\thi')" |perl -0777pe "s/\t/ /g"
hi
I think others have clarified this adequately for other approaches (sed, AWK, etc.). However, my bash-specific answers (tested on macOS High Sierra and CentOS 6/7) follow.
1) If OP wanted to use a search-and-replace method similar to what they originally proposed, then I would suggest using perl for this, as follows. Notes: backslashes before parentheses for regex shouldn't be necessary, and this code line reflects how $1 is better to use than \1 with perl substitution operator (e.g. per Perl 5 documentation).
perl -pe 's/(.*)/\t$1/' $filename > $sedTmpFile && mv $sedTmpFile $filename
2) However, as pointed out by ghostdog74, since the desired operation is actually to simply add a tab at the start of each line before changing the tmp file to the input/target file ($filename), I would recommend perl again but with the following modification(s):
perl -pe 's/^/\t/' $filename > $sedTmpFile && mv $sedTmpFile $filename
## OR
perl -pe $'s/^/\t/' $filename > $sedTmpFile && mv $sedTmpFile $filename
3) Of course, the tmp file is superfluous, so it's better to just do everything 'in place' (adding -i flag) and simplify things to a more elegant one-liner with
perl -i -pe $'s/^/\t/' $filename
TAB=$(printf '\t')
sed "s/${TAB}//g" input_file
It works for me on Red Hat, which will remove tabs from the input file.
If you know that certain characters are not used, you can translate "\t" into something else.
cat my_file | tr "\t" "," | sed "s/(.*)/,\1/"
What is the correct way to parse a string using regular expressions in a linux shell script? I wrote the following script to print my SO rep on the console using curl and sed (not solely because I'm rep-crazy - I'm trying to learn some shell scripting and regex before switching to linux).
json=$(curl -s http://stackoverflow.com/users/flair/165297.json)
echo $json | sed 's/.*"reputation":"\([0-9,]\{1,\}\)".*/\1/' | sed s/,//
But somehow I feel that sed is not the proper tool to use here. I heard that grep is all about regex and explored it a bit. But apparently it prints the whole line whenever a match is found - I am trying to extract a number from a single line of text. Here is a downsized version of the string that I'm working on (returned by curl).
{"displayName":"Amarghosh","reputation":"2,737","badgeHtml":"\u003cspan title=\"1 silver badge\"\u003e\u003cspan class=\"badge2\"\u003e●\u003c/span\u003e\u003cspan class=\"badgecount\"\u003e1\u003c/span\u003e\u003c/span\u003e"}
I guess my questions are:
What is the correct way to parse a string using regular expressions in a linux shell script?
Is sed the right thing to use here?
Could this be done using grep?
Is there any other command that's more easier/appropriate?
The grep command will select the desired line(s) from many but it will not directly manipulate the line. For that, you use sed in a pipeline:
someCommand | grep 'Amarghosh' | sed -e 's/foo/bar/g'
Alternatively, awk (or perl if available) can be used. It's a far more powerful text processing tool than sed in my opinion.
someCommand | awk '/Amarghosh/ { do something }'
For simple text manipulations, just stick with the grep/sed combo. When you need more complicated processing, move on up to awk or perl.
My first thought is to just use:
echo '{"displayName":"Amarghosh","reputation":"2,737","badgeHtml"'
| sed -e 's/.*tion":"//' -e 's/".*//' -e 's/,//g'
which keeps the number of sed processes to one (you can give multiple commands with -e).
You may be interested in using Perl for such tasks. As a demonstration, here is a Perl script which prints the number you want:
#!/usr/local/bin/perl
use warnings;
use strict;
use LWP::Simple;
use JSON;
my $url = "http://stackoverflow.com/users/flair/165297.json";
my $flair = get ($url);
my $parsed = from_json ($flair);
print "$parsed->{reputation}\n";
This script requires you to install the JSON module, which you can do with just the command cpan JSON.
For working with JSON in shell script, use jsawk which like awk, but for JSON.
json=$(curl -s http://stackoverflow.com/users/flair/165297.json)
echo $json | jsawk 'return this.reputation' # 2,747
My proposition:
$ echo $json | sed 's/,//g;s/^.*reputation...\([0-9]*\).*$/\1/'
I put two commands in sed argument:
s/,//g is used to remove all commas, in particular the ones that are present in the reputation value.
s/^.*reputation...\([0-9]*\).*$/\1/ locates the reputation value in the line and replaces the whole line by that value.
In this particular case, I find that sed provides the most compact command without loss of readability.
Other tools for manipulating strings (not only regex) include:
grep, awk, perl mentioned in most of other answers
tr for replacing characters
cut, paste for handling multicolumn inputs
bash itself with its rich $(...) syntax for accessing variables
tail, head for keeping last or first lines of a file
sed is appropriate, but you'll spawn a new process for every sed you use (which may be too heavyweight in more complex scenarios). grep is not really appropriate. It's a search tool that uses regexps to find lines of interest.
Perl is one appropriate solution here, being a shell scripting language with powerful regexp features. It'll do most everything you need without spawning out to separate processes (unlike normal Unix shell scripting) and has a huge library of additional functions.
You can do it with grep. There is -o switch in grep witch extract only matching string not whole line.
$ echo $json | grep -o '"reputation":"[0-9,]\+"' | grep -o '[0-9,]\+'
2,747
1) What is the correct way to parse a string using regular expressions in a linux shell script?
Tools that include regular expression capabilities include sed, grep, awk, Perl, Python, to mention a few. Even newer version of Bash have regex capabilities. All you need to do is look up the docs on how to use them.
2) Is sed the right thing to use here?
It can be, but not necessary.
3) Could this be done using grep?
Yes it can. you will just construct similar regex as you would if you use sed, or others. Note that grep just does what it does, and if you want to modify any files, it will not do it for you.
4) Is there any other command that's easier/more appropriate?
Of course. regex can be powerful, but its not necessarily the best tool to use everytime. It also depends on what you mean by "easier/appropriate".
The other method to use with minimal fuss on regex is using the fields/delimiter approach. you look for patterns that can be "splitted". for eg, in your case(i have downloaded the 165297.json file instead of using curl..(but its the same)
awk 'BEGIN{
FS="reputation" # split on the word "reputation"
}
{
m=split($2,a,"\",\"") # field 2 will contain the value you want plus the rest
# Then split on ":" and save to array "a"
gsub(/[:\",]/,"",a[1]) # now, get rid of the redundant characters
print a[1]
}' 165297.json
output:
$ ./shell.sh
2747
sed is a perfectly valid command for your task, but it may not be the only one.
grep may be useful too, but as you say it prints the whole line. It's most useful for filtering the lines of a multi-line file, and discarding the lines you don't want.
Efficient shell scripts can use a combination of commands (not just the two you mentioned), exploiting the talents of each.
Blindly:
echo $json | awk -F\" '{print $8}'
Similar (the field separator can be a regex):
awk -F'{"|":"|","|"}' '{print $5}'
Smarter (look for the key and print its value):
awk -F'{"|":"|","|"}' '{for(i=2; i<=NF; i+=2) if ($i == "reputation") print $(i+1)}'
You can use a proper library (as others noted):
E:\Home> perl -MLWP::Simple -MJSON -e "print from_json(get 'http://stackoverflow.com/users/flair/165297.json')->{reputation}"
or
$ perl -MLWP::Simple -MJSON -e 'print from_json(get "http://stackoverflow.com/users/flair/165297.json")->{reputation}, "\n"'
depending on OS/shell combination.
Simple RegEx via Shell
Disregarding the specific code in question, there may be times when you want to do a quick regex replace-all from stdin to stdout using shell, in a simple way, using a string syntax similar to JavaScript.
Below are some examples for anyone looking for a way to do this. Perl is a better bet on Mac since it lacks some sed options. If you want to get stdin as a variable you can use MY_VAR=$(cat);.
echo 'text' | perl -pe 's/search/replace/g'; # using perl
echo 'text' | sed -e 's/search/replace/g'; # using sed
And here's an example of a custom, reusable regex function. Arguments are source string (or -- for stdin), search, replace, and options.
regex() {
case "$#" in
( '0' ) exit 1 ;; ( '1' ) echo "$1"; exit 0 ;;
( '2' ) REP='' ;; ( '3' ) REP="$3"; OPT='' ;;
( * ) REP="$3"; OPT="$4" ;;
esac
TXT="$1"; SRCH="$2";
if [ "$1" = "--" ]; then [ ! -t 0 ] && read -r TXT; fi
echo "$TXT" | perl -pe 's/'"$SRCH"'/'"$REP"'/'"$OPT";
}
echo 'text' | regex -- search replace g;