I have a read loop that is reading a variable but not behaving the way I expect. I want to read every line of my variable and process each one. Here is my loop:
while read -r line
do
echo $line | sed 's/<\/td>/<\/td>$/g' | cut -d'$' -f2,3,4 >> file.txt
done <<< "$TABLE"
I expect it to process every line of the file but instead it just does the first one. If my the middle is simply echo $line >> file.txt it works as expected. What's going on here? How do I get the behavior I want?
It seems your lines are delimited by \r instead of \n.
Use this while loop to iterate the input with use of read -d $'\r':
while read -rd $'\r' line; do
echo "$line" | sed 's~</td>~</td>$~g' | cut -d'$' -f2,3,4 >> file.txt
done <<< "$TABLE"
If $TABLE contains a multi-line string, I recommend
printf '%s\n' "$TABLE" |
while read -r line; do
echo $line | sed 's/<\/td>/<\/td>$/g' | cut -d'$' -f2,3,4 >> file.txt
done
This is also more portable since the '<<<' operator for here-strings is not POSIX.
Related
I have piped the output of ls command into a file. The contents are like so:
[Chihiro]_Grisaia_no_Kajitsu_-_01_[1920x816_Blu-ray_FLAC][D2B961D6].mkv
[Chihiro]_Grisaia_no_Kajitsu_-_02_[1920x816_Blu-ray_FLAC][38F88A81].mkv
[Chihiro]_Grisaia_no_Kajitsu_-_03_[1920x816_Blu-ray_FLAC][410F74F7].mkv
My attempt to rename these episodes according to episode number is as follows:
cat grisaia | while read line;
#get the episode number
do EP=$(echo $line | egrep -o "_([0-9]{2})_" | cut -d "_" -f2)
if [[ $EP ]]
#escape special characters
then line=$(echo $line | sed 's/\[/\\[/g' | sed 's/\]/\\]/g')
mv "$line" "Grisaia_no_Kajitsu_${EP}.mkv"
fi
done
The mv commands exit with code 1 with the following error:
mv: cannot stat
'\[Chihiro\]_Grisaia_no_Kajitsu_-01\[1920x816_Blu-ray_FLAC\]\[D2B961D6\].mkv':
No such file or directory
What I really don't get is that if I copy the file that could not be stat and attempt to stat the file, it works. I can even take the exact same string that is output and execute the mv command individually.
If you surround your variable ($line) with double quotes (") you don't need to escape those special characters. So you have two options there:
Remove the following assignation completely:
then # line=$(echo $line | sed 's/\[/\\[/g' | sed 's/\]/\\]/g')`
or
Remove the double quotes in the following line:
mv $line "Grisaia_no_Kajitsu_${EP}.mkv"
Further considerations
Parsing the output of ls is never a good idea. Think about filenames with spaces. See this document for more information.
The cat here is unnecessary:
cat grisaia | while read line;
...
done
Use this instead to avoid an unnecessary pipe:
while read line;
...
done < grisaia
Why is good to avoid pipes in some scenarios? (answering comment)
Pipes create subshells (which are expensive), and you can also make some mistakes as the following:
last=""
cat grisaia | while read line; do
last=$line
done
echo $last # surprise!! it outputs an empty string
The reason is that $last inside the loop belongs to another subshell.
Now, see the same approach wothout pipes:
while read line; do
last=$line
done < grisaia
echo $last # it works as expected and prints the last line
The examplary code below writes hi in a new line at every iteration. Is there a way to prevent this?
#!/bin/bash
while read line; do
var=$(echo $line | cut -d \, -f 2)
echo -n " $var"
done < file.csv > output.txt
Desired output is a concatenation of '$var's at each iteration. The code is run in OS X.
[Resolved]
In most cases of similar problems, klashww's answer would be what you want to try so that I would accept it as the answer. Yet, in my case, such options all failed in fixing the bug. The behavior was due to non-displayed character '^M' at the end of each line, since the file was coming from windows. I relearned that we should make sure to get rid of '^M' before processing it in bash via the line below. After that, the original code works fine.
tr -d '\015' < file > newfile
You might like to try using pure bash:
while IFS=',' read nu1 var nu2; do
echo -n " $var"
done < file.csv > output.txt
nu: "not used"
Use echo "hi\c" instead of echo -n "hi" or printf if avaliable , example printf "hi".
In your example, this should work:
while read line; do
var=$(echo $line | cut -d \, -f 2)
printf " $var"
done < file.csv > output.txt
Or you can use a better tool:
awk -F\, '{printf " "$2}' file.csv > output.txt
If everything fails tr brute force:
echo " $var"| tr -d '\n'
I have a file which contains one line of text with tabs
echo -e "foo\tbar\tfoo2\nx\ty\tz" > file.txt
I'd like to get the first column with cut. It works if I do
$ cut -f 1 file.txt
foo
x
But if I read it in a bash script
while read line
do
new_name=`echo -e $line | cut -f 1`
echo -e "$new_name"
done < file.txt
Then I get instead
foo bar foo2
x y z
What am I doing wrong?
/edit: My script looks like that right now
while IFS=$'\t' read word definition
do
clean_word=`echo -e $word | external-command'`
echo -e "$clean_word\t<b>$word</b><br>$definition" >> $2
done < $1
External command removes diacritics from a Greek word. Can the script be optimized any further without changing external-command?
What is happening is that you did not quote $line when reading the file. Then, the original tab-delimited format was lost and instead of tabs, spaces show in between words. And since cut's default delimiter is a TAB, it does not find any and it prints the whole line.
So quoting works:
while read line
do
new_name=`echo -e "$line" | cut -f 1`
#----------------^^^^^^^
echo -e "$new_name"
done < file.txt
Note, however, that you could have used IFS to set the tab as field separator and read more than one parameter at a time:
while IFS=$'\t' read name rest;
do
echo "$name"
done < file.txt
returning:
foo
x
And, again, note that awk is even faster for this purpose:
$ awk -F"\t" '{print $1}' file.txt
foo
x
So, unless you want to call some external command while looping the file, awk (or sed) is better.
I am trying to run this command:
./smstocurl SLASH2.911325850268888.911325850268896
smstocurl script:
#SLASH2.911325850268888.911325850268896
model=$(echo \&model=$1 | cut -d'.' -f 1)
echo $model
imea1=$(echo \&simImea1=$1 | cut -d'.' -f 2)
echo $imea1
imea2=$(echo \&simImea2=$1 | cut -d'.' -f 3)
echo $imea2
echo $model$imea1$imea2
Result Received
&model=SLASH2911325850268888911325850268896
Result Expected
&model=SLASH2&simImea1=911325850268888&simImea2=911325850268896
What am I missing here ?
You are cutting based on the dot .. In the first case your desired string contains the first string, the one containing &model, so then it is printed.
However, in the other cases you get the 2nd and 3rd blocks (-f2, -f3), so that the imea text gets cutted off.
Instead, I would use something like this:
while IFS="." read -r model imea1 imea2
do
printf "&model=%s&simImea1=%s&simImea2=%s\n" $model $imea1 $imea2
done <<< "$1"
Note the usage of printf and variables to have more control about what we are writing. Using a lot of escapes like in your echos can be risky.
Test
while IFS="." read -r model imea1 imea2; do printf "&model=%s&simImea1=%s&simImea2=%s\n" $model $imea1 $imea2
done <<< "SLASH2.911325850268888.911325850268896"
Returns:
&model=SLASH2&simImea1=911325850268888&simImea2=911325850268896
Alternatively, this sed makes it:
sed -r 's/^([^.]*)\.([^.]*)\.([^.]*)$/\&model=\1\&simImea1=\2\&simImea2=\3/' <<< "$1"
by catching each block of words separated by dots and printing back.
You can also use this way
Run:
./program SLASH2.911325850268888.911325850268896
Script:
#!/bin/bash
String=`echo $1 | sed "s/\./\&simImea1=/"`
String=`echo $String | sed "s/\./\&simImea2=/"`
echo "&model=$String
Output:
&model=SLASH2&simImea1=911325850268888&simImea2=911325850268896
awk way
awk -F. '{print "&model="$1"&simImea1="$2"&simImea2="$3}' <<< "SLASH2.911325850268888.911325850268896"
or
awk -F. '$0="&model="$1"&simImea1="$2"&simImea2="$3' <<< "SLASH2.911325850268888.911325850268896"
output
&model=SLASH2&simImea1=911325850268888&simImea2=911325850268896
I'm trying to write a little script which will open a text file and give me an md5 hash for each line of text. For example I have a file with:
123
213
312
I want output to be:
ba1f2511fc30423bdbb183fe33f3dd0f
6f36dfd82a1b64f668d9957ad81199ff
390d29f732f024a4ebd58645781dfa5a
I'm trying to do this part in bash which will read each line:
#!/bin/bash
#read.file.line.by.line.sh
while read line
do
echo $line
done
later on I do:
$ more 123.txt | ./read.line.by.line.sh | md5sum | cut -d ' ' -f 1
but I'm missing something here, does not work :(
Maybe there is an easier way...
Almost there, try this:
while read -r line; do printf %s "$line" | md5sum | cut -f1 -d' '; done < 123.txt
Unless you also want to hash the newline character in every line you should use printf or echo -n instead of echo option.
In a script:
#! /bin/bash
cat "$#" | while read -r line; do
printf %s "$line" | md5sum | cut -f1 -d' '
done
The script can be called with multiple files as parameters.
You can just call md5sum directly in the script:
#!/bin/bash
#read.file.line.by.line.sh
while read line
do
echo $line | md5sum | awk '{print $1}'
done
That way the script spits out directly what you want: the md5 hash of each line.
this worked for me..
cat $file | while read line; do printf %s "$line" | tr -d '\r\n' | md5 >> hashes.csv; done