How do I insert data into files at a time?
Consider if I have like data below:
echo "hi" >> file1
echo "hi" >> file2
How can I redirect the same "hi" into file1 and file2 simultaneously?
$ echo hi | tee -a file1 file2
See the tee manpage.
Related
I am trying to achieve something like this with bash script:
c.txt:
contents of a.txt
###
contents of b.txt
Basically I want to write a constant string between the contents of two files and save to a new one without modifying the originals.
This was the closest I could get:
echo "###" >> a.txt|cat b.txt >> out.txt
Using - as a filename usually means to use standard input. Thus:
echo 'something' | cat a.txt - b.txt > new.txt
You could do it with three commands:
cat a.txt > out.txt
echo "###" >> out.txt
cat b.txt >> out.txt
And perhaps make a function out of it:
append_hash() { cat $1 > $3; echo "###" >> $3; cat $2 >> $3; }
Usage:
append_hash a.txt b.txt out.txt
I have two files: file1 and file2.
Any match in file2 should append "-W" to the word in file1.
File1:
Verb=Applaud,Beg,Deliver
Adjective=Bitter,Salty,Minty
Adverb=Quickly,Truthfully,Firmly
file2:
Gate
Salty
Explain
Quickly
Hook
Deliver
Earn
Jones
Applaud
Take
Output:
Verb=Applaud-W,Beg,Deliver-W
Adjective=Bitter,Salty-W,Minty
Adverb=Quickly-W,Truthfully,Firmly
Tried but not working and may take too long:
for i in `cat file2` ; do
nawk -v DEE="$i" '{gsub(DEE, DEE"-W")}1' file1 > newfile
mv newfile file1
done
This should work:
sed 's=^=s/\\b=;s=$=\\b/\&-W/g=' file2 | sed -f- file1
Output:
Verb=Applaud-W,Beg,Deliver-W
Adjective=Bitter,Salty-W,Minty
Adverb=Quickly-W,Truthfully,Firmly
To make changes in place:
sed 's=^=s/\\b=;s=$=\\b/\&-W/g=' file2 | sed --in-place -f- file1
Your approach was not that bad but I would prefer sed here, since it has an in place option.
while read i
do
sed -i "s/$i/$i-W/g" file1
done < file2
Here is one using pure bash:
#!/bin/bash
while read line
do
while read word
do
if [[ $line =~ $word ]]; then
line="${line//$word/$word-W}"
fi
done < file2
echo $line
done < file1
An awk:
awk 'BEGIN{FS=OFS=",";RS="=|\n"}
NR==FNR{a[$1]++;next}
{
for (i=1;i<=NF;i++){
$i=($i in a) ? $i"-W":$i
}
printf("%s%s",$0,FNR%2?"=":"\n")
}' file2 file1
Results
Verb=Applaud-W,Beg,Deliver-W
Adjective=Bitter,Salty-W,Minty
Adverb=Quickly-W,Truthfully,Firmly
I was wondering if something like this exist:
tail -f file1 | grep "hello" > fileHello | grep "bye" > fileBye | grep "etc" > fileEtc
echo b1bla >> file1
echo b2hello >> file1
echo b3bye >> file1
echo b4hellobye >> file1
echo b5etc >> file1
echo b6byeetc >> file1
That will make that result :
file1:
b1bla
b2hello
b3bye
b4hellobye
b5etc
b6byeetc
fileHello:
b2hello
b4hellobye
fileBye:
b3bye
b4hellobye
b6byeetc
fileEtc:
b5etc
b6byeetc
Thanks!
Use tee with process substitution:
tail -f file1 | tee >(exec grep "hello" > fileHello) >(exec grep "bye" > fileBye) | grep "etc" > fileEtc
This works, but be aware that piping tail -f is likely to cause some unexpected buffering issues.
tail -f file1 |
awk '/hello/ { print > "fileHello"}
/bye/ { print > "fileBye"}
/etc/ { print > "fileEtc"}'
I have four files and i want to print the 1st line of file1, file2, file3, file4 , then the second line of file1,file2,file3,file4, and then the 3rd line of each file and so on
I tried the following code but it gave me an error:
for i in $(cat $file1)
do
for j in $(cat $file2)
do
for k in $(cat $file3)
do
for l in $(cat $file4)
echo "${i}"
echo "${j}"
echo "${k}"
echo "${l}"
done
done
done
done
so what can i use other than echo ?
There is s tool for that already.
paste "$file1" "$file2" "$file3" "$file4"
Use paste -d $'\n' if you don't want columnar output. (Thanks, #AnsgarWiechers!)
Use paste.
paste file1 file2 file3 file4
Will this do it for you?
paste -d '\n' file1 file2 file3 ...
If you want the contents the files on one line:
paste file1 file2 file3 ...
I have a file called a.txt. with values like
1
2
3
...
I want to overwrite this file but
echo "$var" >> a.txt
echo "$var1" >> a.txt
echo "$var2" >> a.txt
...
just appends. Using > is not useful as well. How can i overwrite with using >> operator in shell script?
You may want to use > for the first redirection and >> for subsequent redirections:
echo "$var" > a.txt
echo "$var1" >> a.txt
echo "$var2" >> a.txt
> truncates the file if it exists, and would do what you originally asked.
>> appends to the file if it exists.
If you want to overwrite the content of a file (not truncate it), use 1<>
e.g.:
[23:58:27 0 ~/tmp] $ echo foobar >a
[23:58:28 0 ~/tmp] $ cat a
foobar
[23:58:50 0 ~/tmp] $ echo -n bar 1<>a
[23:58:53 0 ~/tmp] $ cat a
barbar
In what way is using > not useful? That explicitly does what you want by overwriting the file, so use > for the first and then >> to append future values.
echo "$var
$var1
$var2" > a.txt
or
echo -e "$var\n$var1\n$var2" > a.txt