I want to replace A with T and T with A
sed -e 's/T/A/g;s/A/T/g
as an example above line changes A:T to T:T
I am hoping to get T:A.
How do I do this?
If you want to change single characters, it is simply:
sed 'y/TA/AT/'
If you want to change longer (non-overlapping) strings, you need a temporary value that you know is never used. Conveniently, newline can never appear. So:
sed '
s/T/\n/g
s/A/T/g
s/\n/A/g
'
I'm not a SED expert - so not sure if that can be done as a single command. Just wondering if you've thought about doing that swap like you would in a programming language that would need a temporary variable to do the switch?
Maybe like change the A to a value you know you don't have in the string like Y for example. Then change the T to A and then change Y to T. Would something like that work?
Edit: I did a quick search just out of curiosity. Found this: https://unix.stackexchange.com/questions/528994/swapping-words-with-sed
In case that helps, but with regex stuff, the result is highly dependent on how structured and unique your inputs are. Not sure how to just swap two arbitrary sub-strings or characters throughout an entire string if there's no particular structure that tells you when you're about to get that sub-string or character like the answer above looking for the parenthesis.
Use this Perl one-liner for case-sensitive replacement:
echo 'TATAtata' | perl -pe 'tr{AT}{TA}'
ATATtata
Or this one-liner for case-insensitive replacement:
echo 'TATAtata' | perl -pe 'tr{ATat}{TAta}'
ATATatat
The Perl one-liner uses these command line flags:
-e : Tells Perl to look for code in-line, instead of in a file.
-p : Loop over the input one line at a time, assigning it to $_ by default. Add print $_ after each loop iteration.
SEE ALSO:
perldoc perlrun: how to execute the Perl interpreter: command line switches
perldoc tr
perldoc tr/SEARCHLIST/REPLACEMENTLIST/cdsr
Related
I am trying to find a way to capitalize and replace dashes of a string in one echo. I do not have the ability to use multiple lines for reassigning the string value.
For example:
string='test-e2e-uber' needs to echo $string as TEST_E2E_UBER
I currently can do one or the other by utilizing
${string^^} for capitalization
${string//-/_} for replacement
However, when I try to combine them it does not appear to work (bad substitution error).
Is there a correct syntax to achieve this?
echo ${string^^//-/_}
This does not answer directly your question, but still following script achieves what you wanted :
declare -u string='test-e2e-uber'
echo ${string//-/_}
You can do that directly with the 'tr' command, in just one 'echo'
echo "$string" | tr "-" "_" | tr "[:lower:]" "[:upper:]"
TEST_E2E_UBER
I don't think 'tr' allows to do the conversion of 2 objects in one command only, so I used pipe for output redirection
or you could do something similar with 'awk'
echo "$string" | awk '{gsub("-","_",$0)} {print toupper($0)}'
TEST_E2E_UBER
in this case, I'm replacing with 'gsub' the hyphen, then i'm printing the whole record to uppercase
Why do you dislike it so much to have two successive assignment statements? If you really hate it, you will have to revert to some external program to do the task for you, such as
string=$(tr a-z- A-Z_ <<<$string)
but I would consider it a waste of resources to create a child process for such a simple operation.
Example:
"word" -nothing
To
word" - nothing
in gvim.
I tried
:%s/^.*\"/
But what I get is: -nothing
Well I am new to scripting so I would like to know if it can be done in any other way like using gvim or awk or sed.
In vim... Check for \(word + quote + space + hyphen\) as first reference, followed directly by another \(word\) as second reference... replace by first reference + space + second reference... Make sure the find/replace can happen multiple times on a line with g suffix.
:%s/\(\w" -\)\(\w\)/\1 \2/g
Note that I left out the leading quote... I suppose it is possible you might have spaces in the quoted text - and I think this form might be better for you. Now in sed, that is the really cool thing about the relationship between *nix tools - they all use similar (or the same) regular expressions pattern language. So, the same exact pattern as above can be done in sed (using : as delimiter for clarity).
sed 's:\(\w" -\)\(\w\):\1 \2:g'
Awk doesn't do back references; so, not to say it can't be done, but it is not so convenient.
Could you please try following and let me know if this helps you.
awk '{sub(/^"/,"");sub(/-/,"- ")} 1' Input_file
Solution 2nd: With sed.
sed 's/^"//;s/-/- /' Input_file
Since you also tagged grep: GNU grep has the -P switch for PCRE (Perl compatible reg ex) which has \K: Keep the stuff left of the \K, don't include it in $&, so:
$ echo \"word\" | grep -oP "\"\Kword\""
word"
If I understand your question correctly you want to replace first " in each line with empty string. So in sed it is just:
sed 's/"//'
Without g flag it will replace only first occurrence in each line.
EDIT:
The same way it will work in Vim (unless you have 'gdefault' option set), so in Vim you can:
:%s/"//
try this :
:%s/\"(.*)\"/\1\"/gc
my goal is to sed the 100th line and convert it to a string, then separate the data of the sentence to word
#!/bin/bash
fid=log.txt;
sentence=`expr sed -n '100p' ${fid}`;
for word in $sentence
do
echo $word
done
but apparently this has failed.
expr: syntax error
would somebody please let me know what have I done wrong? previously for number it worked.
The expr does not seem to serve a useful purpose here, and if it did, a sed command would certainly not be a valid or useful thing to pass to it, under most circumstances. You should probably just take it out.
However, the following loop is also problematic. Unquoted variables in shell script are very frequently an error. In this case, you can't quote the thing you pass to the for loop (that would cause the loop to only run once, with the loop variable set to the quoted string) but you also cannot prevent the shell from performing wildcard expansion on the unquoted string. So if the string happened to contain *, the shell will expand that to a list of files in the current directory, for example.
Fortunately, this can all be done in an only slightly more complicated sed script.
sed '100!d;s/[ \t]\+/\n/g;q' "$fid"
That is, if the line number is not 100, delete this line and start over with the next line. Otherwise, we are at line 100; replace runs of whitespace with newlines, (print) and quit.
(The backslash escape codes \t and \n are not universally portable; and \+ for repetition is also an optional extension. I believe there are also sed variants which dislike semicolon as a command separator. Consult your sed manual page, experiment, and if everything else fails, maybe switch to Awk or Perl. Just in case, here is a version which works even on Mac OSX:
sed '100!d
s/[ ][ ]*/\
/g;q' log.txt
The stuff inside the square brackets are a space and a literal tab; in Bash, with default keybindings, type ctrl-V, tab to produce a literal tab.)
Incidentally, this also gets rid of the variable capture antipattern. There are good reasons to capture output to a variable, but if it can be avoided, you often end up with a simpler, more robust and efficient, as well as more idiomatic and elegant script. (I see no reason to put the log file name in a variable, either, in this isolated case; but in a larger script, it might make sense.)
I don't think you need expr command in this case.
expr is used to do calculations. Something like:
expr 1 + 1
Just this one is fine:
sentence=`sed -n '100p' ${fid}`;
#!/bin/bash
fid=log.txt;
sentence=$(sed -n '100p' ${fid});
for word in $sentence
do
echo $word
done
put a dollar sign and parenthesis solve the problem
Im trying to replace numbers in my textfile by adding one to them. i.e.
sed 's/3/4/g' path.txt
sed 's/2/3/g' path.txt
sed 's/1/2/g' path.txt
Instead of this, Can i automate it, i.e. find a /d and add one to it in the replace.
Something like
sed 's/\([0-8]\)/\1+1/g' path.txt
Also wanted to capture more than one digit i.e. ([0-9])\t([0-9]) and change each one keeping the tab inbetween
Thanks
edited #2
Using the perl example,
I also would like it to work with more digits i.e.
perl -pi~ -e 's/(\d+)\.(\d+)\.(\d+)\.(\d+)/ ($1+1)\.($2+1)\.($3+1)\.($4+1) /ge' output.txt
Any tips on making the above work?
There is no support for arithmetic in sed, but you can easily do this in Perl.
perl -pe 's/(\d+)/ $1+1 /ge'
With the /e option, the replacement expression needs to be valid Perl code. So to handle your final updated example, you need
perl -pi~ -e 's/(\d+)\.(\d+)\.(\d+)\.(\d+)/ $1+1 . "." $2+1 . "." . $3+1 . "." . $4+1 /ge'
where strings are properly quoted and adjacent strings are concatenated together with the . Perl string concatenation operator. (The arithmetic numbers are coerced into strings as well when they are concatenated with a string.)
... Though of course, the first script already does that more elegantly, since with the /g flag it already increments every sequence of digits with one, anywhere in the string.
Triplee's perl solution is the more generic answer, but Michal's sed solution works well for this particular case. However, Michal's sed solution is more easily written:
sed y/12345678/23456789/ path.txt
and is better implemented as
tr 12345678 23456789 < path.txt
This utterly fails to handle 2 digit numbers (as in the edited question).
You can do it with sed but it's not easy, see this thread.
And it's hard with awk too, see this.
I'd rather use perl for this (something like this can be seen in action # ideone):
perl -pe 's/([0-8])/$1+1/e'
(The ideone.com example must have some looping as ideone does not sets -pe by default.)
You can't do addition directly in sed - you could do it in awk by matching numbers using a regex in each line and increasing the value, but it's quite complicated. If do not need to handle arbitrary numbers but a limited set, like only single-digit numbers from 0 to 8, you can just put several replacement commands on a single sed command line by separating them with semicolons:
sed 's/8/9/g ; s/7/8/g; s/6/7/g; s/5/6/g; s/4/5/g; s/3/4/g; s/2/3/g; s/1/2/g; s/0/1/g' path.txt
This might work for you (GNU sed & Bash):
sed 's/[0-9]/$((&+1))/g;s/.*/echo "&"/e' file
This will add one to every individual digit, to increment numbers:
sed 's/[0-9]\+/$((&+1))/g;s/.*/echo "&"/e' file
N.B. This method is fraught with problems and may cause unexpected results.
Wow, this one has really got me. Gonna need some tricky sed skill here I think. Here is the output value of command text I'm trying to replace:
...
fast
n : abstaining from food
The value I'd like to replace it with, is:
...
Noun
: abstaining from food
This turns out to be tricker that I thought. Because 'fast' is listed a number of times and because it is listed in other places at the beginning of the line. So I came up with this to define the range:
sed '/fast/,/^ n : / s/fast/Noun/'
Which I thought would do, but... Unfortunately, this doesn't end the replacement and the rest of the output following this match are replaced with Noun. How to get sed to stop replacement after the match? Even better, can I find a two line pattern match and replace it?
Try this:
sed "h; :b; \$b ; N; /^${1}\n n/ {h;x;s//Noun\n/; bb}; \$b ; P; D"
Unfortunately, Paul's answer reads the whole file in which makes any additional processing you might want to do difficult. This version reads the lines in pairs.
By enclosing the sed script in double quotes instead of single quotes, you can include shell variables such as positional parameters. I would recommend surrounding them with curly braces so they are set apart from the adjacent characters. When using double quotes, you'll have to be careful of the shell wanting to do its various expansions. In this example, I've escaped the dollar signs that signify the last line of the input file for the branch commands. Otherwise the shell will try to substitute the value of a variable $b which is likely to be null thus making sed unhappy.
Another technique would be to use single quotes and close and open them each time you have a shell variable:
sed 'h; :b; $b ; N; /^'${1}'\n n/ {h;x;s//Noun\n/; bb}; $b ; P; D'
# ↑open close↑ ↑open close↑
I'm assuming that the "[/code]" in your expected result is a typo. Let me know if it's not.
This seems to do what you want:
sed -e ':a;N;$!ba;s/fast\n n/Noun\n/'
I essentially stole the answer from here.
This might work for you:
sed '$!N;s/^fast\n\s*n :/Noun\n :/;P;D' file
...
Noun
: abstaining from food