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How do I add a line of text to the middle of a file using bash?
(6 answers)
Closed 10 years ago.
How do insert lines of text into file after a particular line in unix ?
Background: The file is an autogenerated textfile but I manually have to edit it every time it is regenerated to add in 4 additional lines after a particular line. I can gurantee that this line will always be in the file but I cannot guarantee excalty what line it will be on so I want the additional lines to be added on the basis of the position of this line rather than adding to a fixed rownumber. I want to automate this process as it is part of my build process.
I'm using Mac OSX so I can make use of unix comand line tools, but Im not very familiar with such tools and cannot work out how to do this.
EDIT
Thanks for the solution, although I havent managed to get them working yet:
I tried Sed solution
sed -i '/<string>1.0</string>/ a <key>CFBundleHelpBookFolder</key>\
<string>SongKongHelp</string>\
<key>CFBundleHelpBookName</key>\
<string>com.jthink.songkong.Help</string>
' /Applications/SongKong.app/Contents/Info.plist
but get error
sed: 1: "/Applications/SongKong. ...": invalid command code S
and I tried the bash solution
#!/bin/bash
while read line; do
echo "$line"
if [[ "$line" = "<string>1.0</string>"]]; then
cat mergefile.txt # or echo or printf your extra lines
fi
done < /Applications/SongKong.app/Contents/Info.plist
but got error
./buildosx4.sh: line 5: syntax error in conditional expression: unexpected token `;'
./buildosx4.sh: line 5: syntax error near `;'
./buildosx4.sh: line 5: ` if [[ "$line" = "<string>1.0</string>"]]; then'
EDIT 2
Now working, i was missing a space
#!/bin/bash
while read line; do
echo "$line"
if [[ "$line" = "<string>1.0</string>" ]]; then
cat mergefile.txt # or echo or printf your extra lines
fi
done < /Applications/SongKong.app/Contents/Info.plist
Assuming the marker line contains fnord and nothing else;
awk '1;/^fnord$/{print "foo"; print "bar";
print "baz"; print "quux"}' input >output
Another way to look at this is that you want to merge two files at some point in one of the files. If your extra four lines were in a separate file, you could make a more generic tool like this:
#!/usr/bin/awk
BEGIN {
SEARCH=ARGV[1]; # Get the search string from the command line
delete ARGV[1]; # Delete the argument, so subsequent arguments are files
}
# Collect the contents of the first file into a variable
NR==FNR {
ins=ins $0 "\n";
next;
}
1 # print every line in the second (or rather the non-first) file
# Once we're in the second file, if we see the match, print stuff...
$0==SEARCH {
printf("%s", ins); # Using printf instead of print to avoid the extra newline
next;
}
I've spelled this out for ease of documentation; you could obviously shorten it to something that looked more like triplee's answer. You'd invoke this like:
$ scriptname "Text to match" mergefile.txt origfile.txt > outputfile.txt
Done this way, you'd have a tool that could be used to achieve this kind of merge on different files and with different text.
Alternately, you could of course do this in pure bash.
#!/bin/bash
while read line; do
echo "$line"
if [[ "$line" = "matchtext" ]]; then
cat mergefile.txt # or echo or printf your extra lines
fi
done < origfile.txt
The problem can be solved efficiently for any filesize by this algorithm:
Read each line from the original file and print it to a tempfile.
If the last line was the marker line, print your insertion lines to the tempfile
Print the remaining lines
Rename the tempfile to the original filename.
As a Perl script:
#!perl
use strict; use warnings;
$^I = ".bak"; # create a backup file
while (<>) {
print;
last if /regex to determine if this is the line/;
}
print <<'END';
Yourstuff
END
print while <>; # print remaining lines
# renaming automatically done.
Testfile:
foo
bar
baz
qux
quux
Regex is /^ba/.
Usage: $ perl this_script.pl source-file
The testfile after processing:
foo
bar
Yourstuff
baz
qux
quux
use the sed 'a command with a regex for the line you need to match
sed -i '/the target line looks like this/ a this is line 1\
this is line 2\
this is line 3\
this is line 4
' FILENAME
Related
I want to replace a line with the $var.
runnew has
input= input/old/should/change;
replace= input/old/replace;
other = input/old/other;
replace_other= input/old/replace_other;
My output file should look like,
input= input/old/should/New;
replace= input/old/New_replace;
other = input/old/New_other;
replace_other= input/old/New_replace_other;
I want to replace "input =" by input = input/old/should/New;
I have used like,
if ($#ARGV != 0) {
die "\n********USAGE <cellname> <tech>********\n";
}
$newinput=$ARGV[0];
open(my $fh, "$runnew") or die "Could not open rerun.txt: $!";
while (<$fh>) {
system ( sed -i "/input=.*/c\input= $newinput" $runnew );
}
But there is error popping up "Scalar found where operator expected at run.pl" and its displaying sed line and asking " (Missing operator before $runnew?)."
When I used same sed on terminal its replacing the line .
Please can anyone point out where the error is ?
Yes Using Sed is simple but I have file with different lines and each line should be replaced .
Please let me knoe if you have better idea than this.
Thanks in advance.
system() takes a list of strings as its argument. You you need to put quotes around the command you pass it.
system ( "sed -i '/input=.*/c\input= $newinput' $runnew" );
But your code still looks very strange. You're running exactly the same sed command for every line in the input file. Is that what you meant to do?
It's not really clear what you're trying to do here. But I'm confident that the best approach would involve not using sed and using Perl to make your transformations.
Why do you want to call sed at all? Your requirement can be much easier handled in Perl directly:
add -i.bak to enable in-place replacement mode
use the first command line parameter as replacement string
remove it from the #ARGV array so it will not be interpreted as file
loop over all files on the command line
read line by line
apply substitution
print result
Perl automatically takes care of opening the files, writing to the correct file and renaming old files to .bak.
#!/usr/bin/perl -i.bak
use warnings;
use strict;
my($replacement) = shift(#ARGV);
while (<>) {
s/input=.*/input= $replacement/;
print;
}
exit 0;
Test run (taking an educated guess on your input data):
$ cat dummy1.txt.bak
input= test1
input= test2
$ cat dummy2.txt.bak
input= test3
input= test4
$ perl dummy.pl REPLACEMENT dummy1.txt dummy2.txt
$ cat dummy1.txt
input= REPLACEMENT
input= REPLACEMENT
$ cat dummy2.txt
input= REPLACEMENT
input= REPLACEMENT
or to use the contents of the file "rerun.txt":
$ perl dummy.pl REPLACEMENT $(cat rerun.txt)
I have a file that contains:
$conf['minified_version'] = 100;
I want to increment that 100 with sed, so I have this:
sed -r 's/(.*minified_version.*)([0-9]+)(.*)/echo "\1$((\2+1))\3"/ge'
The problem is that this strips the $conf from the original, along with any indentation spacing. What I have been able to figure out is that it's because it's trying to run:
echo " $conf['minified_version'] = $((100+1));"
so of course it's trying to replace the $conf with a variable which has no value.
Here is an awk version:
$ awk '/minified_version/{$3+=1} 1' file
$conf['minified_version'] = 101
This looks for lines that contain minified_version. Anytime such a line is found the third field, $3, is incremented by.
My suggested approach to this would be to have a file on-disk that contained nothing but the minified_version number. Then, incrementing that number would be as simple as:
minified_version=$(< minified_version)
printf '%s\n' "$(( minified_version + 1 ))" >minified_version
...and you could just put a sigil in your source file where that needs to be replaced. Let's say you have a file named foo.conf.in that contains:
$conf['minified_version'] = #MINIFIED_VERSION#
...then you could simply run, in your build process:
sed -e "s/#MINIFIED_VERSION#/$(<minified_version)/g" <foo.conf.in >foo.conf
This has the advantage that you never have code changing foo.conf.in, so you don't need to worry about bugs overwriting the file's contents. It also means that if you're checking your files into source control, so long as you only check in foo.conf.in and not foo.conf you avoid potential merge conflicts due to context near the version number changing.
Now, if you did want to do the native operation in-place, here's a somewhat overdesigned approach written in pure native bash (reading from infile and writing to outfile; just rename outfile back over infile when successful to make this an in-place replacement):
target='$conf['"'"'minified_version'"'"'] = '
suffix=';'
while IFS= read -r line; do
if [[ $line = "$target"* ]]; then
value=${line##*=}
value=${value%$suffix}
new_value=$(( value + 1 ))
printf '%s\n' "${target}${new_value}${suffix}"
else
printf '%s\n' "$line"
fi
done <infile >outfile
Trying to do this sort of thing in perl:
sed '1 a<!-- $Header: $\n Purpose: system generated file -->' -i test.xml
Add the header block and purpose to line #2 in the file for xml, shell scripts, etc...
Don't want to do this either:
`sed '1 a<!-- \$Header: \$\n Purpose: system generated file -->' -i test.xml`
But realize it's an option if absolutely necessary.
If you only pass one file, you can use the following:
perl -i -pe'
$_ .= "<!-- \$Header: \$\n Purpose: system generated file -->\n" if $. == 1;
' test.xml
If you might pass multiple files, you'll need to add a line so that $. is reset at the end of each file.
perl -i -pe'
$_ .= "<!-- \$Header: \$\n Purpose: system generated file -->\n" if $. == 1;
close(ARGV) if eof;
' test*.xml
(Note: eof() means something different than just eof. how awful is that!)
I added line breaks for readability. The commands will work as is, but you can remove the line breaks if you so desire.
Try this way:
perl -ple '++$i == 2 and $_ = "changed" # change $_ as you want' in.txt > out.txt
I have this:
perl -pi -e 'print "code I want to insert\n" if $. == 2' *.php
which puts the line code I want to insert on the second line of the file, which is what I need done to every single PHP file
If I run it in a directory with both PHP files and non-PHP files it does the right thing, but only to one PHP file. I thought *.php would apply it to all PHP files, but it doesn't do it.
How can I write it so it will modify every PHP file in a directory? Bonus if there is an easy way to do this recursively through all directories. I don't mind running the Perl script for each directory as there aren't that many, but don't want to hand edit every single file.
The problem is that the file handle ARGV that Perl uses to read the files passed on the command line is never explicitly closed, so the line number $. just keeps incrementing after the end of the first file and never goes back to one.
Fix this by closing ARGV when it has reached end of file. Perl will reopen it to read the next file in the list, and so reset $.
perl -i -pe 'print "code I want to insert\n" if $. == 2; close ARGV if eof' *.php
If you can use sed, this should work:
sed -si '2i\CODE YOU WANT TO INSERT' *.php
To do it recursively, you might try:
find -name '*.php' -execdir sed -si '2i\CODE YOU WANT TO INSERT' '{}' +
Using File::Find.
Note, I've included 3 sanity checks to verify that things are actually being processed they way that you want.
Initially the script will just print out the found files until you comment out the bare return.
Then the script will save backups unless you uncomment the unlink statement.
Finally, the script will only process a single file until you comment out the exit statement.
These three checks are just so you can verify that everything is working as you desire before editing a whole directory tree.
use strict;
use warnings;
use File::Find;
my $to_insert = "code I want to insert\n";
find(sub {
return unless -f && /\.php$/;
print "Edit $File::Find::name\n";
return; # Comment out once satisfied with found files
local $^I = '.bak';
local #ARGV = $_;
while (<>) {
print $to_insert if $. == 2 && $_ ne $to_insert;
print;
}
# unlink "$_$^I"; # Uncomment to delete backups once certain that first file is processed correctly.
exit; # Comment out once certain that first file is processed correctly
}, '.')
I have a file that has some entries like
--ERROR--- Failed to execute the command with employee Name="shayam" Age="34"
--Successfully executed the command with employee Name="ram" Age="55"
--ERROR--- Failed to execute the command with employee Name="sam" Age="23"
--ERROR--- Failed to execute the command with employee Name="yam" Age="3"
I have to extract only the Name and Age of those for whom the command execution was failed.
in this case i need to extract shayam 34 sam 23 yam 3. I need to do this in perl. thanks a lot..
perl -p -e 's/../../g' file
Or to inline replace:
perl -pi -e 's/../../g' file
As a one-liner:
perl -lne '/^--ERROR---.*Name="(.*?)" Age="(.*?)"/ && print "$1 $2"' file
Your title makes it not clear. Anyway...
while(<>) {
next if !/^--ERROR/;
/Name="([^"]+)"\s+Age="([^"]+)"/;
print $1, " ", $2, "\n";
}
can do it reading from stdin; of course, you can change the reading loop to anything else and the print with something to populate an hash or whatever according to your needs.
As a one liner, try:
perl -ne 'print "$1 $2\n" if /^--ERROR/ && /Name="(.*?)"\s+Age="(.*?)"/;'
This is a lot like using sed, but with Perl syntax.
The immediate question of "how do I use perl like sed?" is best answered with s2p, the sed to perl converter. Given the command line, "sed $script", simply invoke "s2p $script" to generate a (typically unreadable) perl script that emulates sed for the given set of commands.
Refer to comments :
my #a = <>; # Reading entire file into an array
chomp #a; # Removing extra spaces
#a = grep {/ERROR/} #a; # Removing lines that do not contain ERROR
# mapping with sed-like regexp to keep only names and ages :
#a = map {s/^.*Name=\"([a-z]+)\" Age=\"([0-9]+)\".*$/$1 $2/; $_} #a;
print join " ",#a; # print of array content