Check all files in directory whether they contain specific string two or more times

Question

I would like to check all files in a directory whether they can contain two or more occurrences of a string.

Checking for a single "occurrence of a specific string using bash" seems easy:

if grep -q "LineString" "$File"; then
  Some Actions # SomeString was found
fi

But how to count to two?

Use the `-c` switch. That will return the count of matching lines as grep's output — Vasan, May 08 '18 at 19:22
Can you give us a sample of the file and the string to be searched — Inian, May 08 '18 at 19:22

codeforester · Accepted Answer · 2018-05-08T21:05:11.257

1

Use (( )) for the numeric comparison:

if (( $(grep -c -- "LineString" "$file") >= 2 )); then
  # your logic
fi

To loop through all files:

#!/bin/bash
shopt -s nullglob # make glob expand to nothing if there are no matching files
for file in *; do
    [[ -f $file ]] || continue
    if (( $(grep -c -- "LineString" "$file") >= 2 )); then
      # your logic
    fi
done

If you are dealing with very huge files and your grep supports the -m option, then you can use grep -cm 2 to optimize the reads:

#!/bin/bash
shopt -s nullglob
for file in *; do
    [[ -f $file ]] || continue
    if (( $(grep -cm 2 -- "LineString" "$file") >= 2 )); then
      # your logic
    fi
done

edited May 08 '18 at 21:05

answered May 08 '18 at 19:45

codeforester

39,467
16
112
140

1

Note that `-c` is a standard option for `grep`, but `-m` is not. (Also, it may depend on the implementation , but `-m` and `-c` can be combined to avoid the need to use `wc -l`.) – chepner May 08 '18 at 20:12
1

From the 2nd answer I'm getting an "unexpected fi" error. Shouldn't I close the for() loop with an done? for file in *; do [[ -f $file ]] || continue filename="${file##*/}" echo $filename if (( $(grep -c -- "LineString" "$file") >= 2 )); then mv $file "$filename.bak" echo "select ST_LineMerge(ST_Union(geometry)) from $file"; ogr2ogr -f GeoJSON -explodecollections -dialect sqlite -sql \ "select ST_LineMerge(ST_Union(geometry)) from $file" "$filename.geojson" "$filename.bak" fi done – agmoermann May 08 '18 at 20:38
Corrected the answer. – codeforester May 08 '18 at 20:45
Thanks @chepner. Updated the answer to incorporate your suggestion. – codeforester May 08 '18 at 21:05
Since merging "MultiLineStrings" doesn't work – can I exclude them from the search? (Sorry, that's a little bit funny!) – agmoermann May 08 '18 at 22:10
That seems like a different requirement. Please update your question appropriately or ask a new question. – codeforester May 08 '18 at 22:49

score 0 · Answer 2 · answered May 08 '18 at 19:28

0

Try this

if [ `grep "LineString" $file | wc -l` -gt 1 ]; then 
    echo "done found";
    ' do something
fi;

answered May 08 '18 at 19:28

Eby Jacob

1,418
1
10
28

Check all files in directory whether they contain specific string two or more times

2 Answers2