I have a CSV of image details I want to loop over in a bash script. awk seems like an obvious choice to loop over the data.
For each row, I want to take the values, and use them to do Imagemagick stuff. The following isn't working (obviously):
awk -F, '{ magick "source.png" "$1.jpg" }' images.csv
GNU AWK excels at processing structured text data, although it can be used to summon commands using system function it is less handy for that than some other language, e.g. python has module of standard library called subprocess which is more feature-rich.
If you wish to use awk for this task anyway, then I suggest preparing output to be feed into bash command, say you have file.txt with following content
file1.jpg,file1.bmp
file2.png,file2.bmp
file3.webp,file3.bmp
and you have files listed in 1st column in current working directory and wish to convert them to files shown in 2nd column and access to convert command, then you might do
awk 'BEGIN{FS=","}{print "convert \"" $1 "\" \"" $2 "\""}' file.txt | bash
which is equvialent to starting bash and doing
convert "file1.jpg" "file1.bmp"
convert "file2.png" "file2.bmp"
convert "file3.webp" "file3.bmp"
Observe that I have used literal " to enclose filenames, so it should work with names containing spaces. Disclaimer: it might fail if name containing special character, e.g. ".
Related
General
I am trying to recursively search through hundreds of JSON files under a specific directory for lines that match a specific regular expression.
grep -rh works great for searching recursively for specific lines. I am having a problem applying a regular expression with the search because all the lines in the JSON files begin with a " and end in either ", or ".
Example: If I want to apply a regular expression to get all the lines that begin with zxc I will not be able to do it because the lines actually begin with "zxc
Code
The following command would work if the lines had no " at the beginning.
/bin/grep -rh -E "^(zxc)" "/etc/json_dir/"
The following command works, but I do not want grep to get hundreds of thousands of lines from all the JSON files and then apply a regular expression afterwards.
/bin/grep -rh -E ".*" "/etc/json_dir/" | /bin/sed -e 's/^"//g' -e 's/,$//g' -e 's/"$//g' | /bin/grep -E "^(zxc)"
Question
Is there a way for grep to ignore the " character at the beginning and " and ", characters at the end of the lines before it applies a regular expression ?
If there's no way, is there a way to do it with some other bash command, perl, python or some other language.
You can go with awk if I understand Your question properly:
awk '{gsub(/^"|"$/,"") } # this part removes all the "s from the start and end of line
/^WHAT/ { print } # or any other processing
' **/*.json
Note: the **/* requires the globestar recursive globbing option in (modern) bash.
See it in action at Ideone.
You can shorten it somewhat to:
awk '/^"?WHAT/' **/* # this executes the default printing action
But awk|sed|grep might not be the right tool to search JSON.
I have a file (lets call it data.csv) similar to this
"123","456","ud,h-match","moredata"
with many rows in the same format and embedded commas. What I need to do is look at the third column and see if it has an expression. In this case I want to know if the third column has "match" anywhere (which it does). If there is any, then I to replace the whole column to something else like "replaced". So to relate it to the example data.csv file, I would want it to look this.
"123","456","replaced","moredata"
Ideally, I want the file data.csv itself to be changed (time is of the essence since I have a big file) but it's also fine if you write it to another file.
Edit:
I have tried using awk:
awk -F'","' -OFS="," '{if(tolower($3) ~ "stringI'mSearchingFor"){$3="replacement"; print}else print}' file
but it dosen't change anything. If I remove the OFS portion then it works but it gets separated by spaces and the columns don't get enclosed by double quotes.
Depending on the answer to my question about what you mean by column, this may be what you want (uses GNU awk for FPAT):
$ awk -v FPAT='[^,]+|"[^"]+"' -v OFS=',' '$3~/match/{$3="\"replaced\""} 1' file
"123","456","replaced","moredata"
Use awk -i inplace ... if you want to do "in place" editing.
With any awk (but slightly more fragile than the above since it leaves the leading/trailing " on the first and last fields, and has no -i inplace):
$ awk 'BEGIN{FS=OFS="\",\""} $3~/match/{$3="replaced"} 1' file
"123","456","replaced","moredata"
I have a simple log file with content like:
1504007980.039:{"key":"valueA"}
1504007990.359:{"key":"valueB", "key2": "valueC"}
...
That I'd like to output to multiple files that each have as content the JSON part that comes after the timestamp. So I would get as a result the files:
1504007980039.json
1504007990359.json
...
This is similar to How to split one text file into multiple *.txt files? but the name of the file should be extracted from each line (and remove an extra dot), and not generated via an index
Preferably I'd want a one-liner that can be executed in bash.
Since you aren't using GNU awk you need to close output files as you go to avoid the "too many open files" error. To avoid that and issues around specific values in your JSON and issues related to undefined behavior during output redirection, this is what you need:
awk '{
fname = $0
sub(/\./,"",fname)
sub(/:.*/,".json",fname)
sub(/[^:]+:/,"")
print >> fname
close(fname)
}' file
You can of course squeeze it onto 1 line if you see some benefit to that:
awk '{f=$0;sub(/\./,"",f);sub(/:.*/,".json",f);sub(/[^:]+:/,"");print>>f;close(f)}' file
awk solution:
awk '{ idx=index($0,":"); fn=substr($0,1,idx-1)".json"; sub(/\./,"",fn);
print substr($0,idx+1) > fn; close(fn) }' input.log
idx=index($0,":") - capturing index of the 1st :
fn=substr($0,1,idx-1)".json" - preparing filename
Viewing results (for 2 sample lines from the question):
for f in *.json; do echo "$f"; cat "$f"; echo; done
The output (filename -> content):
1504007980039.json
{"key":"valueA"}
1504007990359.json
{"key":"valueB"}
I'm creating a Bash script to parse the air pollution levels from the webpage:
http://aqicn.org/city/beijing/m/
There is a lot of stuff in the file, but this is the relevant bit:
"iaqi":[{"p":"pm25","v":[59,21,112],"i":"Beijing pm25 (fine
particulate matter) measured by U.S Embassy Beijing Air Quality
Monitor
(\u7f8e\u56fd\u9a7b\u5317\u4eac\u5927\u4f7f\u9986\u7a7a\u6c14\u8d28\u91cf\u76d1\u6d4b).
Values are converted from \u00b5g/m3 to AQI levels using the EPA
standard."},{"p":"pm10","v":[15,5,69],"i":"Beijing pm10
(respirable particulate matter) measured by Beijing Environmental
Protection Monitoring Center
I want the script to parse and display 2 numbers: current PM2.5 and PM10 levels (the numbers in bold in the above paragraph).
CITY="beijing"
AQIDATA=$(wget -q 0 http://aqicn.org/city/$CITY/m/ -O -)
PM25=$(awk -v FS="(\"p\":\"pm25\",\"v\":\\\[|,[0-9]+)" '{print $2}' <<< $AQIDATA)
PM100=$(awk -v FS="(\"p\":\"pm10\",\"v\":\\\[|,[0-9]+)" '{print $2}' <<< $AQIDATA)
echo $PM25 $PM100
Even though I can get PM2.5 levels to display correctly, I cannot get PM10 levels to display. I cannot understand why, because the strings are similar.
Anyone here able to explain?
The following approach is based on two steps:
(1) Extracting the relevant JSON;
(2) Extracting the relevant information from the JSON using a JSON-aware tool -- here jq.
(1) Ideally, the web service would provide a JSON API that would allow one to obtain the JSON directly, but as the URL you have is intended for viewing with a browser, some form of screen-scraping is needed. There is a certain amount of brittleness to such an approach, so here I'll just provide something that currently works:
wget -O - http://aqicn.org/city/beijing/m |
gawk 'BEGIN{RS="function"}
$1 ~/getAqiModel/ {
sub(/.*var model=/,"");
sub(/;return model;}/,"");
print}'
(gawk or an awk that supports multi-character RS can be used; if you have another awk, then first split on "function", using e.g.:
sed $'s/function/\\\n/g' # three backslashes )
The output of the above can be piped to the following jq command, which performs the filtering envisioned in (2) above.
(2)
jq -c '.iaqi | .[]
| select(.p? =="pm25" or .p? =="pm10") | [.p, .v[0]]'
The result:
["pm25",59]
["pm10",15]
I think your problem is that you have a single line HTML file that contains a script that contains a variable that contains the data you are looking for.
Your field delimiters are either "p":"pm100", "v":[ or a comma and some digits.
For pm25 this works, because it is the first, and there are no occurrences of ,21 or something similar before it.
However, for pm10, there are some that are associated with pm25 ahead of it. So the second field contains the empty string between ,21 and ,112
#karakfa has a hack that seems to work -- but he doesn't explain very well why it works.
What he does is use awk's record separator (which is usually a newline) and sets it to either of :, ,, or [. So in your case, one of the records would be "pm25", because it is preceded by a colon, which is a separator, and succeeded by a comma, also a separator.
Once it hits the matching content ("pm25") it sets a counter to 4. Then, for this and the next records, it counts this counter down. "pm25" itself, "v", the empty string between : and [, and finally reaches one when hitting the record with the number you want to output: 4 && ! 3 is false, 3 && ! 2 is false, 2 && ! 1 is false, but 1 && ! 0 is true. Since there is no execution block, awk simply prints this record, which is the value you want.
A more robust work would probably be using xpath to find the script, then use some json parser or similar to get the value.
chw21's helpful answer explains why your approach didn't work.
peak's helpful answer is the most robust, because it employs proper JSON parsing.
If you don't want to or can't use third-party utility jq for JSON parsing, I suggest using sed rather than awk, because awk is not a good fit for field-based parsing of this data.
$ sed -E 's/^.*"pm25"[^[]+\[([0-9]+).+"pm10"[^[]+\[([0-9]+).*$/\1 \2/' <<< "$AQIDATA"
59 15
The above should work with both GNU and BSD/OSX sed.
To read the result into variables:
read pm25 pm10 < \
<(sed -E 's/^.*"pm25"[^[]+\[([0-9]+).+"pm10"[^[]+\[([0-9]+).*$/\1 \2/' <<< "$AQIDATA")
Note how I've chosen lowercase variable names, because it's best to avoid all upper-case variables in shell programming, so as to avoid conflicts with special shell and environment variables.
If you can't rely on the order of the values in the source string, use two separate sed commands:
pm25=$(sed -E 's/^.*"pm25"[^[]+\[([0-9]+).*$/\1/' <<< "$AQIDATA")
pm10=$(sed -E 's/^.*"pm10"[^[]+\[([0-9]+).*$/\1/' <<< "$AQIDATA")
awk to the rescue!
If you have to, you can use this hacky way using smart counters with hand-crafted delimiters. Setting RS instead of FS transfers looping through fields to awk itself. Multi-char RS is not available for all awks (gawk supports it).
$ awk -v RS='[:,[]' '$0=="\"pm25\""{c=4} c&&!--c' file
59
$ awk -v RS='[:,[]' '$0=="\"pm10\""{c=4} c&&!--c' file
15
I'm inserting a git diff of changed files into a JSON object to send using a curl request.
The problem is it doesn't like the new-line characters being inserted into the JSON but I'm not sure how to get around that. Translate tool didn't work, this perl solution I'm using is close but just replaces with spaces:
changedfiles=$(git diff --name-only $3..$4 | perl -p -e 's/\n/ /')
and changing it to this didn't help:
changedfiles=$(git diff --name-only $3..$4 | perl -p -e 's/\n/\\n/')
Can anyone point me in the right direction? It doesn't need to use perl, it just needs to work
(...being simple would be nice too)
Instead of trying to do ad-hoc escaping for characters that your immediate testing finds problematic, how about using an actual JSON library that handles all of them in a solid way?
Here's an example in bash using inlined python:
python -c '
import json
import sys
print(json.dumps({"data": sys.argv[1]}))
' "$(git diff --name-only $3..$4)"
It prints the json object { "data": "your command output here" } with standards compliant escaping.
This is what I think you want to do to get a quoted list of files separated by commas (i.e. for inserting into a JSON string):
git diff --name-only $3..$4 | perl -p -e 's/(.*)/"$1",/;s/\n//;s/""/","/'
This works if your files don't contain double quotes or special characters that need to be JSON escaped.
First, we put the files in quotes followed by a comma, then remove newlines, then change the "" between files to ",". Although, this is kind of a hack. Somewhat better might be:
git diff --name-only $3..$4 | perl -p -e '$/="";s/(.*)\n/"$1",/g;s/,$//'
Here we read in the whole input, newlines and all, do our substitution and remove the final comma.