I am writing a script which requires me to find the parent directory of the existing directory.
Suppose I have a directory called deep which is under /path/is/very/deep/. I need to find the "path" directory but not "/".
Tried couple of combination of code but seems I am stuck in a dead lock.
Appreciate any help.
here is my code which is not working.
if [ $dir_name != "/" || $path != "/" ]
then
path=`dirname $dir_name`
dir_name=`dirname $path`
echo $path
else
dir_name=$path
echo $dirname
fi
here is an alternative way to solve your problem:
Generally all you need to do is to remove all characters in the string after (and including) the second / character. Linux Terminals have the sed function that allows you to do it.
try out this line in your Terminal/code:
echo '/path/is/very/deep' | sed -r 's:^(/[^/]*).*$:\1:'
you can remove the echo command and assign it to any variable in your code as you wish.
Edit: In sed the backslash (/) is also used as a delimiter character, you have to escape it with a forward slash (\). Parentheses are also escaped for some reason.
path="$( echo "${dir_name}" | sed -e 's|/[^/]*/\{0,1\}$||;s|^$|/|' )"
(posix compliant) and work for /, /bla, /bla/, bla/bla, ...
Related
I have lot filenames which have this kind format:
118-edorf.sum.fil
118-edorf.sum.fil_1
118-edorf.sum.fil_11
i want to remove 118-edorf.sum. from the filename and get only the extension , fil , fil_1 and fil_11 and rename it to asc, asc_1 and asc_11.
So far, i can only remove 118-edorf.sum. using
sed 's/.*\.//'
The result will be
fil
fil_1
fil_11
So, how to rename it to
asc
asc_1
asc_11
To your solution only add additional substitution
sed 's/^.*\.//; s/fil/asc/'
To rename all files in directory using that criteria
rename 's/^.*\.//; s/fil/asc/' *
note: this rename command is untested
You can try this zsh foreach loop. Foreach can be somewhat slow for many files. You can also remove the echo statements for less noisier output.
foreach C (`ls 118-edorf.sum.fil*`)
f2=`echo $C|cut -d "." -f 3|cut -s -d "_" -f 2`
if [ "${f2}" -eq "" ]; then
echo "no underscore"
mv $C asc
elif
echo "_${f2}"
mv $C "asc_${f2}"
end
This might work for you (GNU sed):
sed -r 's/.*\.([^_]*(.*))/mv \1 asc\2/e' file
Use an evaluated substitution command. The substitution removes everything upto the last . and retains everything thereafter as the first backreference. Everything following the first _ within that backreference is also retained as the second backreference. The RHS of the substitution command the forms a mv commmand using the parts from the LHS.
If your sed does not have the e command/flag, use:
sed 's/.*\.\([^_]*\(.*\)\)/mv \1 asc\2/' file | shell
It might be safer to use:
sed -r 's/.*\.(fil(.*))/mv \1 asc\2/e' file
I'm trying to write a script to swap out text in a file:
sed s/foo/bar/g myFile.txt > myFile.txt.updated
mv myFile.txt.updated myFile.txt
I evoke the sed program, which swaps out text in myFile.txt and redirects the changed lines of text to a second file. mv then moves .updated txt file to myFile.txt, overwriting it. That command works in the shell.
I wrote:
#!/bin/sh
#First, I set up some descriptive variables for the arguments
initialString="$1"
shift
desiredChange="$1"
shift
document="$1"
#Then, I evoke sed on these (more readable) parameters
updatedDocument=`sed s/$initialString/$desiredChange/g $document`
#I want to make sure that was done properly
echo updated document is $updatedDocument
#then I move the output in to the new text document
mv $updatedDocument $document
I get the error:
mv: target `myFile.txt' is not a directory
I understand that it thinks my new file's name is the first word of the string that was sed's output. I don't know how to correct that. I've been trying since 7am and every quotation, creating a temporary file to store the output in (disastrous results), IFS...everything so far gives me more and more unhelpful errors. I need to clear my head and I need your help. How can I fix this?
Maybe try
echo $updatedDocument > $document
Change
updatedDocument=`sed s/$initialString/$desiredChange/g $document`
to
updatedDocument=${document}.txt
sed s/$initialString/$desiredChange/g $document
Backticks will actually put the entire piped output of the sed command into your variable value.
An even faster way would be to not use updatedDocument or mv at all by doing an in-place sed:
sed -i s/$initialString/$desiredChange/g $document
The -i flag tells sed to do the replacement in-place. This basically means creating a temp file for the output and replacing your original file with the temp file once it is done, pretty much exactly as you are doing.
#!/bin/sh
#First, I set up some descriptive variables for the arguments
echo "$1" | sed #translation of special regex char like . * \ / ? | read -r initialString
echo "$2" | sed 's|[\&/]|\\&|g' | read -r desiredChange
document="$3"
#Then, I evoke sed
sed "s/${initialString}/${desiredChange}/g" ${document} | tee ${document}
don't forget that initialString and desiredChange are pattern interpreted as regex, so a trnaslation is certainly needed
sed #translation of special regex char like . * \ / ? is to replace by the correct sed (discuss on several post on the site)
I have a string " r1/pkg/amd64/misc/hash/hash-r1.r5218.tbz"
but, I only want "hash-r1.r5218.tbz"
so, I try this
unix$ a="r1/pkg/amd64/misc/hash/hash-r1.r5218.tbz"
unix$ echo $a | sed 's/.*\/\([^\/]*\)\.tbz/\1/' //[1]
hash-r1.r5218 //I know this should work
unix$ echo $a | sed 's/.*\/\([^\/]+\)\.tbz/\1/' //[2]
r1/pkg/amd64/misc/hash/hash-r1.r5218.tbz //however I do not know why it does not work.
as far as I remember, + in regexp, means using previous regexp 1 or more times. * in regexp, means using previous regexp 0 or more times.
Could anyone explain why [2] fails, thanks a lot.
a="r1/pkg/amd64/misc/hash/hash-r1.r5218.tbz"
echo $a | sed 's:.*/::; s:.tbz$::'
hash-r1.r5218
You don't need to use '/' as the patern/repl marker, you can use other chars. The ':' is very popular.
Also, you don't have to use capture buffers, when you know the exact text on both sides of your target data.
I have substituted out all chars up to the last '/', relying on .* for all chars, and '/' to terminate the standard greedy search of sed. THe you sub out the trailing \.tbz with noting.
IHTH.
Not all versions of sed support + in the regex. Some that do support it require -r to be specified. But why use sed instead of basename or echo ${a##*/}?
Using this submatch via parentheses will grab everything after the last slash to the end of your line.
str="r1/pkg/amd64/misc/hash/hash-r1.r5218.tbz"
echo $str | sed -n -E -e 's/.+\/(.+)$/\1/p'
returns hash-r1.r5218.tbz
Oh, and your #2 fails because sed by default prints out each line that has a match. Using the -n flag suppresses that, and the trailing 'p' on this regex prints out the replace part of the substitution.
For grep there's a fixed string option, -F (fgrep) to turn off regex interpretation of the search string.
Is there a similar facility for sed? I couldn't find anything in the man. A recommendation of another gnu/linux tool would also be fine.
I'm using sed for the find and replace functionality: sed -i "s/abc/def/g"
Do you have to use sed? If you're writing a bash script, you can do
#!/bin/bash
pattern='abc'
replace='def'
file=/path/to/file
tmpfile="${TMPDIR:-/tmp}/$( basename "$file" ).$$"
while read -r line
do
echo "${line//$pattern/$replace}"
done < "$file" > "$tmpfile" && mv "$tmpfile" "$file"
With an older Bourne shell (such as ksh88 or POSIX sh), you may not have that cool ${var/pattern/replace} structure, but you do have ${var#pattern} and ${var%pattern}, which can be used to split the string up and then reassemble it. If you need to do that, you're in for a lot more code - but it's really not too bad.
If you're not in a shell script already, you could pretty easily make the pattern, replace, and filename parameters and just call this. :)
PS: The ${TMPDIR:-/tmp} structure uses $TMPDIR if that's set in your environment, or uses /tmp if the variable isn't set. I like to stick the PID of the current process on the end of the filename in the hopes that it'll be slightly more unique. You should probably use mktemp or similar in the "real world", but this is ok for a quick example, and the mktemp binary isn't always available.
Option 1) Escape regexp characters. E.g. sed 's/\$0\.0/0/g' will replace all occurrences of $0.0 with 0.
Option 2) Use perl -p -e in conjunction with quotemeta. E.g. perl -p -e 's/\\./,/gi' will replace all occurrences of . with ,.
You can use option 2 in scripts like this:
SEARCH="C++"
REPLACE="C#"
cat $FILELIST | perl -p -e "s/\\Q$SEARCH\\E/$REPLACE/g" > $NEWLIST
If you're not opposed to Ruby or long lines, you could use this:
alias replace='ruby -e "File.write(ARGV[0], File.read(ARGV[0]).gsub(ARGV[1]) { ARGV[2] })"'
replace test3.txt abc def
This loads the whole file into memory, performs the replacements and saves it back to disk. Should probably not be used for massive files.
If you don't want to escape your string, you can reach your goal in 2 steps:
fgrep the line (getting the line number) you want to replace, and
afterwards use sed for replacing this line.
E.g.
#/bin/sh
PATTERN='foo*[)*abc' # we need it literal
LINENUMBER="$( fgrep -n "$PATTERN" "$FILE" | cut -d':' -f1 )"
NEWSTRING='my new string'
sed -i "${LINENUMBER}s/.*/$NEWSTRING/" "$FILE"
You can do this in two lines of bash code if you're OK with reading the whole file into memory. This is quite flexible -- the pattern and replacement can contain newlines to match across lines if needed. It also preserves any trailing newline or lack thereof, which a simple loop with read does not.
mapfile -d '' < file
printf '%s' "${MAPFILE//"$pat"/"$rep"}" > file
For completeness, if the file can contain null bytes (\0), we need to extend the above, and it becomes
mapfile -d '' < <(cat file; printf '\0')
last=${MAPFILE[-1]}; unset "MAPFILE[-1]"
printf '%s\0' "${MAPFILE[#]//"$pat"/"$rep"}" > file
printf '%s' "${last//"$pat"/"$rep"}" >> file
perl -i.orig -pse 'while (($i = index($_,$s)) >= 0) { substr($_,$i,length($s), $r)}'--\
-s='$_REQUEST['\'old\'']' -r='$_REQUEST['\'new\'']' sample.txt
-i.orig in-place modification with backup.
-p print lines from the input file by default
-s enable rudimentary parsing of command line arguments
-e run this script
index($_,$s) search for the $s string
substr($_,$i,length($s), $r) replace the string
while (($i = index($_,$s)) >= 0) repeat until
-- end of perl parameters
-s='$_REQUEST['\'old\'']', -r='$_REQUEST['\'new\'']' - set $s,$r
You still need to "escape" ' chars but the rest should be straight forward.
Note: this started as an answer to How to pass special character string to sed hence the $_REQUEST['old'] strings, however this question is a bit more appropriately formulated.
You should be using replace instead of sed.
From the man page:
The replace utility program changes strings in place in files or on the
standard input.
Invoke replace in one of the following ways:
shell> replace from to [from to] ... -- file_name [file_name] ...
shell> replace from to [from to] ... < file_name
from represents a string to look for and to represents its replacement.
There can be one or more pairs of strings.
I am using the below code for replacing a string
inside a shell script.
echo $LINE | sed -e 's/12345678/"$replace"/g'
but it's getting replaced with $replace instead of the value of that variable.
Could anybody tell what went wrong?
If you want to interpret $replace, you should not use single quotes since they prevent variable substitution.
Try:
echo $LINE | sed -e "s/12345678/${replace}/g"
Transcript:
pax> export replace=987654321
pax> echo X123456789X | sed "s/123456789/${replace}/"
X987654321X
pax> _
Just be careful to ensure that ${replace} doesn't have any characters of significance to sed (like / for instance) since it will cause confusion unless escaped. But if, as you say, you're replacing one number with another, that shouldn't be a problem.
you can use the shell (bash/ksh).
$ var="12345678abc"
$ replace="test"
$ echo ${var//12345678/$replace}
testabc
Not specific to the question, but for folks who need the same kind of functionality expanded for clarity from previous answers:
# create some variables
str="someFileName.foo"
find=".foo"
replace=".bar"
# notice the the str isn't prefixed with $
# this is just how this feature works :/
result=${str//$find/$replace}
echo $result
# result is: someFileName.bar
str="someFileName.sally"
find=".foo"
replace=".bar"
result=${str//$find/$replace}
echo $result
# result is: someFileName.sally because ".foo" was not found
Found a graceful solution.
echo ${LINE//12345678/$replace}
Single quotes are very strong. Once inside, there's nothing you can do to invoke variable substitution, until you leave. Use double quotes instead:
echo $LINE | sed -e "s/12345678/$replace/g"
Let me give you two examples.
Using sed:
#!/bin/bash
LINE="12345678HI"
replace="Hello"
echo $LINE | sed -e "s/12345678/$replace/g"
Without Using sed:
LINE="12345678HI"
str_to_replace="12345678"
replace_str="Hello"
result=${str//$str_to_replace/$replace_str}
echo $result
Hope you will find it helpful!
echo $LINE | sed -e 's/12345678/'$replace'/g'
you can still use single quotes, but you have to "open" them when you want the variable expanded at the right place. otherwise the string is taken "literally" (as #paxdiablo correctly stated, his answer is correct as well)
To let your shell expand the variable, you need to use double-quotes like
sed -i "s#12345678#$replace#g" file.txt
This will break if $replace contain special sed characters (#, \). But you can preprocess $replace to quote them:
replace_quoted=$(printf '%s' "$replace" | sed 's/[#\]/\\\0/g')
sed -i "s#12345678#$replace_quoted#g" file.txt
I had a similar requirement to this but my replace var contained an ampersand. Escaping the ampersand like this solved my problem:
replace="salt & pepper"
echo "pass the salt" | sed "s/salt/${replace/&/\&}/g"
use # if you want to replace things like /. $ etc.
result=$(echo $str | sed "s#$oldstr#$newstr#g")
the above code will replace all occurrences of the specified replacement term
if you want, remove the ending g which means that the only first occurrence will be replaced.
Use this instead
echo $LINE | sed -e 's/12345678/$replace/g'
this works for me just simply remove the quotes
I prefer to use double quotes , as single quptes are very powerful as we used them if dont able to change anything inside it or can invoke the variable substituion .
so use double quotes instaed.
echo $LINE | sed -e "s/12345678/$replace/g"