In the following shell script, how do I insert ${today} into a separate existing file index.html at line 4? (Line 1-3 in index.html already has some code. Line 4 is empty. Line 5-EOL has some html code.)
#!/bin/sh
Today=$(date "+%Y.%m.%d-%H.%M.%S")
#insert ${today} into a separate existing file (index.html) in line 4
#<to-do>
I'd use awk for this:
awk 'NR==4 {print strftime("%Y.%m.%d-%H.%M.%S", systime())} 1' file
You can also pass in a variable if you don't want to generate the date string inside awk:
Today=$(date "+%Y.%m.%d-%H.%M.%S")
awk -vtoday=$Today 'NR==4 {print today} 1' file
The sed utility can insert text at specific lines. This might not be the best way to express it; it overwrites anything it finds on line 4.
Today=$(date "+%Y.%m.%d-%H.%M.%S")
sed -i -e "4s/^.*$/$Today/" index.html
The -i argument tells sed to edit in place--it effectively overwrites the input file. I think this option makes sed a better choice than awk for your problem. For testing, remove the -i argument, and it will write to stdout instead.
If you want this to work only if line 4 is a blank line (no whitespace, no characters), use this instead.
Today=$(date "+%Y.%m.%d-%H.%M.%S")
sed -i -e "4s/^$/$Today/" index.html
Related
I need to delete from a file all the words that do not contain any uppercase in bash.
I use the sed command but the output is the same as the input:
I tried sed 's/[^0-9]*//' file
Example input:
sjasd
ksaLK
asdn
Asdw
Output
ksaLK
Asdw
Could you please try following.
sed -n '/[A-Z]/p' Input_file
As per #PaulHodges's comment, once you are happy with results use sed -i .... option in above code to make changes in Input_file itself.
To make a file without those:
grep '[A-Z]' infile > outfile
This is a nondestructive way to check first. Then you could replace the old file with the new one.
If you really want to edit the existing file in place:
sed -i '/[A-Z]/!d' infile
This says to delete all lines that do not have a capital letter.
How can I use a cat and sed to read data from a file and insert it into another file under known line?
For example I have a file named script1.txt that contains a few hundred lines, one of the line has the value "COMMANDS="commands"
If I wanted use sed to insert a line under it, simply I can use sed as the command bellow.
sed -i '/^COMMANDS=.*/a NEW LINE HERE' script1.txt
But if I want to insert a multi lines and these lines inside a file, and these line changes every a few hours.. how can i do that ?
I tried:
DATA=$(cat data.txt)
sed -i '/^COMMANDS=.*/a '$DATA'' script1.txt
I got the error bellow.
sed: -e expression #1, char 1: unknown command: `"'
Is there a way other than sed to insert the data from file under known line with no issues?
This might work for you (GNU sed):
sed -i '/^COMMANDS=/r dataFile' file
This will append the contents of the file dataFile after the line beginning COMMANDS= and update file
If the data you want to append is multi-line, you might want to replace newlines with \n.
#!/bin/sh
DATA="$(awk '{gsub(/[]\/$*.^&[]/, "\\\\&");printf (FNR>1)?"\\n%s":"%s",$0}END{print ""}' data.txt)"
sed -i -e '/^COMMANDS=.*/a\' -e "$DATA" script1.txt
Here the awk command escapes sed special characters (for basic regular expressions), then prints "%s" for the first line, and "\\n%s" for the others. A newline is printed at the end, but it's somewhat pointless as $() strips it anyway.
The sed command is almost the same but multiple expressions are used which is equivalent to a multi-line sed script (The a text sed alternative syntax can act weirdly with leading spaces/backslashes).
I have a file, which has multiple lines.
For example:
a
ab#
ad.
a12fs
b
c
...
I want to use sed or awk delete the line, if the line include symbols or numbers. (For example, I want to delete: ab#, ad., a12fs.... lines)
or in another words, I just want to keep the line which include [a-z][A-Z] .
I know how to delete number line,
sed '/[0-9]/d' file.txt
but I do not know how to delete symbols lines.
Or there has any easy way to do that?
To keep blank lines:
grep '^[[:alpha:]]*$' file
sed '/[^[:alpha:]]/d' file
awk '/^[[:alpha:]]*$/' file
To remove blank lines:
grep '^[[:alpha:]]+$' file
sed -E -n '/^[[:alpha:]]+$/p' file
awk '/^[[:alpha:]]+$/' file
grep works well too and is even simpler: just do the reverse: keep the lines that interest you, which are way easier to define
grep -i '^[a-z]*$' file.txt
(match lines containing only letters and empty lines, and -i option makes grep case-insensitive)
to remove empty lines as well:
grep -i '^[a-z]+$' file.txt
caution when using Windows text files, as there's a carriage return at the end of the line, so nothing would match depending on grep versions (tested on windows here and it works)
but just in case:
grep -iP '^[a-z]*\r?$'
(note the P option to enable perl expressions or \r is not recognized)
You can use this sed:
sed '/^[A-Za-z0-9]\+$/!d' file
(OR)
sed '/[^A-Za-z0-9]/d' file
$ awk '!/[^[:alpha:]]/' file.txt
a
b
c
My text file contains 100 lines and the text file surely contains Technology and /Technology words .In which ,I want to remove Technology and /Technology words present in the file using shell scripting.
sed -i.bak -e 's#/Technology##g' -e 's#Technology##g' my_text_file
This is delete the words and also make a backup of the original file just in case
sed -i -e 's#/Technology##g' -e 's#Technology##g' my_text_file
This will not make a backup but just modify the original file
You can try this one.
sed -r 's/<[\/]*technology>//g' a
Here is an awk
cat file
This Technology
More here
Mine /Technology must go
awk '{gsub(/\/*Technology/,"")}1' file
This
More here
Mine must go
By adding an extra space in the regex, it will not leave an extra space in the output.
awk '{gsub(/\/*Technology /,"")}1' file
This Technology
More here
Mine must go
To write back to original file
awk '{gsub(/\/*Technology /,"")}1' file > tmp && mv tmp file
If you have gnu awk 4.1+ you can do
awk -i '{gsub(/\/*Technology /,"")}1' file
I am new to shell scripting. Just wanna know how can I obtain the result I wanted with the following:
I have two files (FILE_A and FILE_B)
FILE_A contains:
09228606355,71295939,1,http://sun.net.ph/043xafj.xml,01000001C123000D30
09228505450,71295857,1,http://sun.net.ph/004xafk.xml,01000001C123000D30
FILE_B contains:
http://sun.net.ph/161ybfq.xml ,9220002354016,93111
http://sun.net.ph/004xafk.xml ,9220002354074,93111
If the URL (4th field) in FILE_A is present in FILE_B, the out will be:
09228505450,71295857,1,http://sun.net.ph/004xafk.xml,01000001C123000D30,9220002354074,93111
It will display the whole line in FILE_A and added 2nd and 3rd field of FILE_B.
I hope my question is clear. Thank you.
This might work for you (GNU sed):
sed -r 's/^\s*(\S+)\s*,(.*)/\\#^([^,]*,){3}\1#s#$#,\2#p/' fileB | sed -nrf - fileA
This builds a sed script from fileB and runs it against fileA. The second sed script is run in silent mode and only those lines that match the sed script are printed out.
Try this:
paste -d , A B | awk -F , '{if ($4==$6) print "match", $1,$2,$3,$4,$5,$7,$8;}'
I removed the spaces in your file B for the $4==$6 to work.
I use paste to create a composite line using , as the delimiter to get a line with , . I then use awk comparison to check the URLs from both files and if a match is found I print all the fields you care about.