Is there simple equivalent of
sed -i '/str/d' /file
but for multiline variable?
Or I can use only following
var=`echo "$var" | sed "s/str//"`
Use
var=$(echo "$var" | sed '/str/d')
The quotes around $var in the subcommand are important for interpolating the newline characters. Otherwise $var would all be on one line.
You don't need sed, echo, and a pipe just to manipulate a string in bash:
$ echo "$var"
foo
str
bar
$ var="${var//str
}"
$ echo "$var"
foo
bar
man bash.
Related
Need help in making a sed script to find and replace user input along with single quotes. Input file admins.py:
Script:
read adminsid
while [[ $adminsid == "" ]];
do
echo "You did not enter anything. Please re-enter AdminID"
read adminsid
done
## Please enter Admin's ID
9999999999,8888888888,1111111111
## Script To Replace ADMIN_IDS = [] to ADMIN_IDS = ['9999999999,8888888888,1111111111'] in file
sed -i "s|ADMIN_IDS = \[.*\]|ADMIN_IDS = ['$adminsid']|g" $file
## Current results:
ADMIN_IDS = ['9999999999,8888888888,1111111111']
## Expected results:
ADMIN_IDS = ['9999999999','8888888888','1111111111']
Assign the variable to the data
adminsid=9999999999,8888888888,1111111111
Then use sed -e (script) option to add the quoting, and square brackets.
echo "$adminsid" | sed -e "s/,/\',\'/g" -e "s/^/[\'/" -e "s/$/\']/"
or to apply changes to a file (filename in $file):
sed -i "$file" -e "s/,/\',\'/g" -e "s/^/[\'/" -e "s/$/\']/"
You can do this with awk too:
Suppose you have assigned the variable as :
adminsid=9999999999,8888888888,1111111111
Then the solution:
echo "$adminsid"| awk -F"," -v quote="'" -v OFS="','" '$1=$1 {print "["quote $0 quote"]"}'
-F"," -v OFS="','" :: Replacing separator (,) with (',')
print "["quote $0 quote"]" :: Add single quotes(') and ([) and (]) to the begin and end of line
This might work for you (GNU sed & bash):
<<<"$adminsid" sed 's/[^,]\+/'\''&'\''/g;s/.*/[&]/'
Surround all non-comma characters by single quotes and then surround the entire string by square brackets.
Replace the , with ',' in the variable and add characters at the beginning and at the end.
sed "s/.*/['&']/" <<< "${adminsid//,/','}"
echo "('${adminsid//,/\\',\\'}')"
I have a string like this:
string="aaa-bbb"
But I want to add space before char '-', so I want this:
aaa -bbb
I tried a lot of things, but I can't add space there. I tried with echo $string | tr '-' ' -', and some other stuff, but it didn't work...
I have Linux Mint: GNU bash, version 4.3.8(1)
No need to call sed, use string substitution native in BASH:
$ foo="abc-def-ghi"
$ echo "${foo//-/ -}"
abc -def -ghi
Note the two slashes after the variable name: the first slash replaces the first occurrence, where two slashes replace every occurrence.
Bash has builtin string substitution.
$ string="aaa-bbb"
$ result="${string/-/ -}"
$ echo "$result"
aaa -bbb
Alternatively, you can use sed or perl:
$ string="aaa-bbb"
$ result=$(sed 's/-/ -/' <<< $string)
$ echo "$result"
aaa -bbb
$ result=$(perl -pe 's/-/ -/' <<< $string)
$ echo "$result"
aaa -bbb
Give a try to this:
printf "%s\n" "${string}" | sed 's/-/ -/g'
It looks for - and replace it with - (space hyphen)
You are asking the shell to echo an un-quoted variable $string.
When that happens, spaces inside variables are used to split the string:
$ string="a -b -c"
$ printf '<%s>\n' $string
<a>
<-b>
<-c>
The variable does contain the spaces, just that you are not seeing it correctly.
Quote your expansions
$ printf '<%s>\n' "$string"
<a -b -c>
To get your variable changed from - to - there are many solutions:
sed: string="$(echo "$string" | sed 's/-/ -/g')"; echo "$string"
bash: string="${string//-/ -}; echo "$string"
tr can only substitute one character at a time. what you're looking for is sed:
echo "$string" | sed 's/-/ -/'
I have tried this command in bash linux
echo "example=value" | sed "s/^example=\(.*\)$/\1/"
The output is value. But if I put it in a variable, it doesn't work.
For example:
var="example=value" | sed "s/^example=\(.*\)$/\1/"
echo $var
The output is nothing. What wrong?
Do it like this:
var=$(echo example=value | sed "s/^example=\(.*\)$/\1/")
echo $var
assigning a variable doesn't pass the value to sed via pipe.
You can pass while assigning like this:
var="example=value" && echo "$var" | sed "s/^example=\(.*\)$/\1/"
or use a sub shell like this:
var=$(echo "example=value" | sed "s/^example=\(.*\)$/\1/")
You can do this without sed, using shell parameter expansion:
$ var="example=value"
$ var="${var#*=}"
$ echo "$var"
value
I'm trying to extract substring after the last period (dot).
examples below.
echo "filename..txt" should return "txt"
echo "filename.txt." should return ""
echo "filename" should return ""
echo "filename.xml" should return "xml"
I tried below. but works only if the character(dot) exists once. But my filename may have (dot) for 0 or more times.
echo "filename.txt" | cut -d "." -f2
Let's use awk!
awk -F"." '{print (NF>1)? $NF : ""}' file
This sets field separator to . and prints the last one. But if there is none, it prints an empty string.
Test
$ cat file
filename..txt
filename.txt.
filename
filename.xml
$ awk -F"." '{print (NF>1)? $NF : ""}' file
txt
xml
One can make this portable (so it's not Linux-only), avoiding an ERE dependency, with the following:
$ sed -ne 's/.*\.//p' <<< "file..txt"
txt
$ sed -ne 's/.*\.//p' <<< "file.txt."
$ sed -ne 's/.*\.//p' <<< "file"
$ sed -ne 's/.*\.//p' <<< "file.xml"
xml
Note that for testing purposes, I'm using a "here-string" in bash. If your shell is not bash, use whatever your shell uses to feed data to sed.
The important bit here is the use of sed's -n option, which tells it not to print anything by default, combined with the substitute command's explicit p flag, which tells sed to print only upon a successful substitution, which obviously requires a dot to be included in the pattern.
With this solution, the difference between "file.txt." and "file" is that the former returns the input line replaced with null (so you may still get a newline depending on your usage), whereas the latter returns nothing, as sed is not instructed to print, as no . is included in the input. The end result may well be the same, of course:
$ printf "#%s#\n" $(sed -ne 's/.*\.//p' <<< "file.txt.")
##
$ printf "#%s#\n" $(sed -ne 's/.*\.//p' <<< "file")
##
Simple to do with awk:
awk -F"." '{ print $NF }'
What this does: With dot as a delimiter, extract the last field from the input.
Use sed in 2 steps: first remove string without a dot and than remove up to the last dot:
sed -e 's/^[^.]*$//' -e 's/.*\.//'
Test:
for s in file.txt.. file.txt. file.txt filename file.xml; do
echo "$s -> $(echo "$s" | sed -e 's/^[^.]*$//' -e 's/.*\.//')"
done
Testresult:
file.txt.. ->
file.txt. ->
file.txt -> txt
filename ->
file.xml -> xml
Actually the answer of #ghoti is roughly the same, just a bit shorter (better).
This solution can be used by other readers who wants to do something like this in another language.
I am wrinting a shell script and have a variable like this: something-that-is-hyphenated.
I need to use it in various points in the script as:
something-that-is-hyphenated, somethingthatishyphenated, SomethingThatIsHyphenated
I have managed to change it to somethingthatishyphenated by stripping out - using sed "s/-//g".
I am sure there is a simpler way, and also, need to know how to get the camel cased version.
Edit: Working function derived from #Michał's answer
function hyphenToCamel {
tr '-' '\n' | awk '{printf "%s%s", toupper(substr($0,1,1)), substr($0,2)}'
}
CAMEL=$(echo something-that-is-hyphenated | hyphenToCamel)
echo $CAMEL
Edit: Finally, a sed one liner thanks to #glenn
echo a-hyphenated-string | sed -E "s/(^|-)([a-z])/\u\2/g"
a GNU sed one-liner
echo something-that-is-hyphenated |
sed -e 's/-\([a-z]\)/\u\1/g' -e 's/^[a-z]/\u&/'
\u in the replacement string is documented in the sed manual.
Pure bashism:
var0=something-that-is-hyphenated
var1=(${var0//-/ })
var2=${var1[*]^}
var3=${var2// /}
echo $var3
SomethingThatIsHyphenated
Line 1 is trivial.
Line 2 is the bashism for replaceAll or 's/-/ /g', wrapped in parens, to build an array.
Line 3 uses ${foo^}, which means uppercase (while ${foo,} would mean 'lowercase' [note, how ^ points up while , points down]) but to operate on every first letter of a word, we address the whole array with ${foo[*]} (or ${foo[#]}, if you would prefer that).
Line 4 is again a replace-all: blank with nothing.
Line 5 is trivial again.
You can define a function:
hypenToCamel() {
tr '-' '\n' | awk '{printf "%s%s", toupper(substr($0,0,1)), substr($0,2)}'
}
CAMEL=$(echo something-that-is-hyphenated | hypenToCamel)
echo $CAMEL
In the shell you are stuck with being messy:
aa="aaa-aaa-bbb-bbb"
echo " $aa" | sed -e 's/--*/ /g' -e 's/ a/A/g' -e 's/ b/B/g' ... -e 's/ *//g'
Note the carefully placed space in the echo and the double space in the last -e.
I leave it as an exercise to complete the code.
In perl it is a bit easier as a one-line shell command:
perl -e 'print map{ $a = ucfirst; $a =~ s/ +//g; $a} split( /-+/, $ARGV[0] ), "\n"' $aa
For the records, here's a pure Bash safe method (that is not subject to pathname expansion)—using Bash≥4:
var0=something-that-is-hyphenated
IFS=- read -r -d '' -a var1 < <(printf '%s\0' "${var0,,}")
printf '%s' "${var1[#]^}"
This (safely) splits the lowercase expansion of var0 at the hyphens, with each split part in array var1. Then we use the ^ parameter expansion to uppercase the first character of the fields of this array, and concatenate them.
If your variable may also contain spaces and you want to act on them too, change IFS=- into IFS='- '.