I want to ask if is possible to combine linux command and <
sendmail -S "lalalal" -f "dailaakak" -au "kakakak" <<EOF
>lalal:lalal
>opp:ttt
>ggg:zzz
EOF
I want to have something like that sendmail -S "lalalal" -f "dailaakak" -au "kakakak" <<EOF; lalal:lalal; opp:ttt; ggg:zzz; EOF
I need to use that not in bash script
If it has to be in one line without newlines use that:
echo -e "lalal:lalal\nopp:ttt\nggg:zzz" | sendmail -S "lalalal" -f "dailaakak" -au "kakakak"
echo -n interpretes escapes characters such as \n as a newline.
If you are asking whether you can use the << EOF in an interactive shell then the answer is yes, you can.
Note this functionality is called here document and that there can be any word instead of EOF. For example:
$ cat - << someword
> Here you
> can
> write text with as many
> newlines as you want.
> someword
Here you
can
write text with as many
newlines as you want.
(cat - prints whatever it receives on stdin)
For more information on here documents you can read for example this: http://tldp.org/LDP/abs/html/here-docs.html
I have tried and succeeded but it's messy. EOF simply does not like to accept substituted new lines for some reason so it needs to be put in another format. Now I'm sure this could be achieved with an expect script one one line but the below is what I have made and works.
echo "ssh localhost `printf "<< EOF\necho "Working!" >> /tmp/myfile \nEOF\n"`" > file.sh; chmod770 file.sh; ./file.sh
printf "<< EOF\necho Test! >> /tmp/myfile \nEOF\n" | xargs ssh localhost
Please ensure chmod file permissions are suitable for your own work case! Putting it into an environment variable instead of a file is also likely to work.
My code is given below. Echo works fine. But, the moment I redirect output of echo to touch, I get an error "no such file or directory". Why ? How do i fix it ?
If I copy paste the output of only echo, then the file is created, but not with touch.
while read line
do
#touch < echo -e "$correctFilePathAndName"
echo -e "$correctFilePathAndName"
done < $file.txt
If you have file names in each line of your input file file.txt then you don't need to do any loop. You can just do:
touch $(<file.txt)
to create all the files in one single touch command.
You need to provide the file name as argument and not via standard input. You can use command substitution via $(…) or `…`:
while read line
do
touch "$(echo -e "$correctFilePathAndName")"
done < $file.txt
Ehm, lose the echo part... and use the correct variable name.
while read line; do
touch "$line"
done < $file.txt
try :
echo -e "$correctFilePathAndName" | touch
EDIT : Sorry correct piping is :
echo -e "$correctFilePathAndName" | xargs touch
The '<' redirects via stdin whereas touch needs the filename as an argument. xargs transforms stdin in an argument for touch.
I'm trying to write a pretty basic script in Linux shell but I'm still learning. Basically, everything is good to go except one part. I direct two outputs into the same file, e.g.:
echo `losetup -a` > partitionfile
echo "p1" >> partition final
Basically, I need to add the letter/number "p1" to the end of whatever is written in the file.
The problem is, it ends up being read (cat partitionfile) as:
/dev/loop0
p1
I need it on the same line to it reads out as:
/dev/loop0p1
There has to be a way to fix this, I just don't know it. Any help would be much appreciated!
Thanks!
I would go for:
echo "$(losetup -a)p1" > partitionfile
For an example, see the following transcript:
pax> echo "$(echo xyzzy_)p1"
xyzzy_p1
The xyzzy_ is the output of the inner echo command (which in your case would be losetup) and the outer echo command appends p1.
Hi Actually the correct option of echo to achieve this is "\c"
\c Keeps the cursor on the same line.
However you cannot use \c unless you have enabled it with
-e
Thus your code should be something like this ...
echo -e "`losetup -a` \c" > partitionfile
echo "p1" >> partition final
this will write in partitionfile as
< output of losetup -a > p1
everything on same line.
You can pass -n flag to the first echo statement to not print the trailing new line.
Ref: http://linux.die.net/man/1/echo
I need to add the following line to the end of a config file:
include "/configs/projectname.conf"
to a file called lighttpd.conf
I am looking into using sed to do this, but I can't work out how.
How would I only insert it if the line doesn't already exist?
Just keep it simple :)
grep + echo should suffice:
grep -qxF 'include "/configs/projectname.conf"' foo.bar || echo 'include "/configs/projectname.conf"' >> foo.bar
-q be quiet
-x match the whole line
-F pattern is a plain string
https://linux.die.net/man/1/grep
Edit:
incorporated #cerin and #thijs-wouters suggestions.
This would be a clean, readable and reusable solution using grep and echo to add a line to a file only if it doesn't already exist:
LINE='include "/configs/projectname.conf"'
FILE='lighttpd.conf'
grep -qF -- "$LINE" "$FILE" || echo "$LINE" >> "$FILE"
If you need to match the whole line use grep -xqF
Add -s to ignore errors when the file does not exist, creating a new file with just that line.
Try this:
grep -q '^option' file && sed -i 's/^option.*/option=value/' file || echo 'option=value' >> file
Using sed, the simplest syntax:
sed \
-e '/^\(option=\).*/{s//\1value/;:a;n;ba;q}' \
-e '$aoption=value' filename
This would replace the parameter if it exists, else would add it to the bottom of the file.
Use the -i option if you want to edit the file in-place.
If you want to accept and keep white spaces, and in addition to remove the comment, if the line already exists, but is commented out, write:
sed -i \
-e '/^#\?\(\s*option\s*=\s*\).*/{s//\1value/;:a;n;ba;q}' \
-e '$aoption=value' filename
Please note that neither option nor value must contain a slash /, or you will have to escape it to \/.
To use bash-variables $option and $value, you could write:
sed -i \
-e '/^#\?\(\s*'${option//\//\\/}'\s*=\s*\).*/{s//\1'${value//\//\\/}'/;:a;n;ba;q}' \
-e '$a'${option//\//\\/}'='${value//\//\\/} filename
The bash expression ${option//\//\\/} quotes slashes, it replaces all / with \/.
Note: Just trapped into a problem. In bash you may quote "${option//\//\\/}", but in the sh of busybox, this does not work, so you should avoid the quotes, at least in non-bourne-shells.
All combined in a bash function:
# call option with parameters: $1=name $2=value $3=file
function option() {
name=${1//\//\\/}
value=${2//\//\\/}
sed -i \
-e '/^#\?\(\s*'"${name}"'\s*=\s*\).*/{s//\1'"${value}"'/;:a;n;ba;q}' \
-e '$a'"${name}"'='"${value}" $3
}
Explanation:
/^\(option=\).*/: Match lines that start with option= and (.*) ignore everything after the =. The \(…\) encloses the part we will reuse as \1later.
/^#?(\s*'"${option//////}"'\s*=\s*).*/: Ignore commented out code with # at the begin of line. \? means «optional». The comment will be removed, because it is outside of the copied part in \(…\). \s* means «any number of white spaces» (space, tabulator). White spaces are copied, since they are within \(…\), so you do not lose formatting.
/^\(option=\).*/{…}: If matches a line /…/, then execute the next command. Command to execute is not a single command, but a block {…}.
s//…/: Search and replace. Since the search term is empty //, it applies to the last match, which was /^\(option=\).*/.
s//\1value/: Replace the last match with everything in (…), referenced by \1and the textvalue`
:a;n;ba;q: Set label a, then read next line n, then branch b (or goto) back to label a, that means: read all lines up to the end of file, so after the first match, just fetch all following lines without further processing. Then q quit and therefore ignore everything else.
$aoption=value: At the end of file $, append a the text option=value
More information on sed and a command overview is on my blog:
https://marc.wäckerlin.ch/computer/stream-editor-sed-overview-and-reference
If writing to a protected file, #drAlberT and #rubo77 's answers might not work for you since one can't sudo >>. A similarly simple solution, then, would be to use tee --append (or, on MacOS, tee -a):
LINE='include "/configs/projectname.conf"'
FILE=lighttpd.conf
grep -qF "$LINE" "$FILE" || echo "$LINE" | sudo tee --append "$FILE"
Here's a sed version:
sed -e '\|include "/configs/projectname.conf"|h; ${x;s/incl//;{g;t};a\' -e 'include "/configs/projectname.conf"' -e '}' file
If your string is in a variable:
string='include "/configs/projectname.conf"'
sed -e "\|$string|h; \${x;s|$string||;{g;t};a\\" -e "$string" -e "}" file
If, one day, someone else have to deal with this code as "legacy code", then that person will be grateful if you write a less exoteric code, such as
grep -q -F 'include "/configs/projectname.conf"' lighttpd.conf
if [ $? -ne 0 ]; then
echo 'include "/configs/projectname.conf"' >> lighttpd.conf
fi
another sed solution is to always append it on the last line and delete a pre existing one.
sed -e '$a\' -e '<your-entry>' -e "/<your-entry-properly-escaped>/d"
"properly-escaped" means to put a regex that matches your entry, i.e. to escape all regex controls from your actual entry, i.e. to put a backslash in front of ^$/*?+().
this might fail on the last line of your file or if there's no dangling newline, I'm not sure, but that could be dealt with by some nifty branching...
Here is a one-liner sed which does the job inline. Note that it preserves the location of the variable and its indentation in the file when it exists. This is often important for the context, like when there are comments around or when the variable is in an indented block. Any solution based on "delete-then-append" paradigm fails badly at this.
sed -i '/^[ \t]*option=/{h;s/=.*/=value/};${x;/^$/{s//option=value/;H};x}' test.conf
With a generic pair of variable/value you can write it this way:
var=c
val='12 34' # it handles spaces nicely btw
sed -i '/^[ \t]*'"$var"'=/{h;s/=.*/='"$val"'/};${x;/^$/{s//c='"$val"'/;H};x}' test.conf
Finally, if you want also to keep inline comments, you can do it with a catch group. E.g. if test.conf contains the following:
a=123
# Here is "c":
c=999 # with its own comment and indent
b=234
d=567
Then running this
var='c'
val='"yay"'
sed -i '/^[ \t]*'"$var"'=/{h;s/=[^#]*\(.*\)/='"$val"'\1/;s/'"$val"'#/'"$val"' #/};${x;/^$/{s//'"$var"'='"$val"'/;H};x}' test.conf
Produces that:
a=123
# Here is "c":
c="yay" # with its own comment and indent
b=234
d=567
As an awk-only one-liner:
awk -v s=option=value '/^option=/{$0=s;f=1} {a[++n]=$0} END{if(!f)a[++n]=s;for(i=1;i<=n;i++)print a[i]>ARGV[1]}' file
ARGV[1] is your input file. It is opened and written to in the for loop of theEND block. Opening file for output in the END block replaces the need for utilities like sponge or writing to a temporary file and then mving the temporary file to file.
The two assignments to array a[] accumulate all output lines into a. if(!f)a[++n]=s appends the new option=value if the main awk loop couldn't find option in file.
I have added some spaces (not many) for readability, but you really need just one space in the whole awk program, the space after print.
If file includes # comments they will be preserved.
Here's an awk implementation
/^option *=/ {
print "option=value"; # print this instead of the original line
done=1; # set a flag, that the line was found
next # all done for this line
}
{print} # all other lines -> print them
END { # end of file
if(done != 1) # haven't found /option=/ -> add it at the end of output
print "option=value"
}
Run it using
awk -f update.awk < /etc/fdm_monitor.conf > /etc/fdm_monitor.conf.tmp && \
mv /etc/fdm_monitor.conf.tmp /etc/fdm_monitor.conf
or
awk -f update.awk < /etc/fdm_monitor.conf | sponge /etc/fdm_monitor.conf
EDIT:
As a one-liner:
awk '/^option *=/ {print "option=value";d=1;next}{print}END{if(d!=1)print "option=value"}' /etc/fdm_monitor.conf | sponge /etc/fdm_monitor.conf
use awk
awk 'FNR==NR && /configs.*projectname\.conf/{f=1;next}f==0;END{ if(!f) { print "your line"}} ' file file
sed -i 's/^option.*/option=value/g' /etc/fdm_monitor.conf
grep -q "option=value" /etc/fdm_monitor.conf || echo "option=value" >> /etc/fdm_monitor.conf
here is an awk one-liner:
awk -v s="option=value" '/^option/{f=1;$0=s}7;END{if(!f)print s}' file
this doesn't do in-place change on the file, you can however :
awk '...' file > tmpfile && mv tmpfile file
Using sed, you could say:
sed -e '/option=/{s/.*/option=value/;:a;n;:ba;q}' -e 'aoption=value' filename
This would replace the parameter if it exists, else would add it to the bottom of the file.
Use the -i option if you want to edit the file in-place:
sed -i -e '/option=/{s/.*/option=value/;:a;n;:ba;q}' -e 'aoption=value' filename
sed -i '1 h
1 !H
$ {
x
s/^option.*/option=value/g
t
s/$/\
option=value/
}' /etc/fdm_monitor.conf
Load all the file in buffer, at the end, change all occurence and if no change occur, add to the end
The answers using grep are wrong. You need to add an -x option to match the entire line otherwise lines like #text to add will still match when looking to add exactly text to add.
So the correct solution is something like:
grep -qxF 'include "/configs/projectname.conf"' foo.bar || echo 'include "/configs/projectname.conf"' >> foo.bar
Using sed: It will insert at the end of line. You can also pass in variables as usual of course.
grep -qxF "port=9033" $light.conf
if [ $? -ne 0 ]; then
sed -i "$ a port=9033" $light.conf
else
echo "port=9033 already added"
fi
Using oneliner sed
grep -qxF "port=9033" $lightconf || sed -i "$ a port=9033" $lightconf
Using echo may not work under root, but will work like this. But it will not let you automate things if you are looking to do it since it might ask for password.
I had a problem when I was trying to edit from the root for a particular user. Just adding the $username before was a fix for me.
grep -qxF "port=9033" light.conf
if [ $? -ne 0 ]; then
sudo -u $user_name echo "port=9033" >> light.conf
else
echo "already there"
fi
I elaborated on kev's grep/sed solution by setting variables in order to reduce duplication.
Set the variables in the first line (hint: $_option shall match everything on the line up until the value [including any seperator like = or :]).
_file="/etc/ssmtp/ssmtp.conf" _option="mailhub=" _value="my.domain.tld" \
sh -c '\
grep -q "^$_option" "$_file" \
&& sed -i "s/^$_option.*/$_option$_value/" "$_file" \
|| echo "$_option$_value" >> "$_file"\
'
Mind that the sh -c '...' just has the effect of widening the scope of the variables without the need for an export. (See Setting an environment variable before a command in bash not working for second command in a pipe)
You can use this function to find and search config changes:
#!/bin/bash
#Find and Replace config values
find_and_replace_config () {
file=$1
var=$2
new_value=$3
awk -v var="$var" -v new_val="$new_value" 'BEGIN{FS=OFS="="}match($1, "^\\s*" var "\\s*") {$2=" " new_val}1' "$file" > output.tmp && sudo mv output.tmp $file
}
find_and_replace_config /etc/php5/apache2/php.ini max_execution_time 60
If you want to run this command using a python script within a Linux terminal...
import os,sys
LINE = 'include '+ <insert_line_STRING>
FILE = <insert_file_path_STRING>
os.system('grep -qxF $"'+LINE+'" '+FILE+' || echo $"'+LINE+'" >> '+FILE)
The $ and double quotations had me in a jungle, but this worked.
Thanks everyone
Try:
LINE='include "/configs/projectname.conf"'
sed -n "\|$LINE|q;\$a $LINE" lighttpd.conf >> lighttpd.conf
Use the pipe as separator and quit if $LINE has been found. Otherwise, append $LINE at the end.
Since we only read the file in sed command, I suppose we have no clobber issue in general (it depends on your shell settings).
Using only sed I'd suggest the following solution:
sed -i \
-e 's#^include "/configs/projectname.conf"#include "/configs/projectname.conf"#' \
-e t \
-e '$ainclude "/configs/projectname.conf"' lighttpd.conf
s replace the line include "/configs/projectname.conf with itself (using # as delimiter here)
t if the replacement was successful skip the rest of the commands
$a otherwise jump to the last line and append include "/configs/projectname.conf after it
Almost all of the answers work but not in all scenarios or OS as per my experience. Only thing that worked on older systems and new and different flavours of OS is the following.
I needed to append KUBECONFIG path to bashrc file if it doesnt exist. So, what I did is
I assume that it exists and delete it.
with sed I append the string I want.
sed -i '/KUBECONFIG=/d' ~/.bashrc
echo 'export KUBECONFIG=/etc/rancher/rke2/rke2.yaml' >> ~/.bashrc
I needed to edit a file with restricted write permissions so needed sudo. working from ghostdog74's answer and using a temp file:
awk 'FNR==NR && /configs.*projectname\.conf/{f=1;next}f==0;END{ if(!f) { print "your line"}} ' file > /tmp/file
sudo mv /tmp/file file