Examples of using ack

Tue, 16 May 2017 23:59:39 +0000

Find instances of `ToDo` in source files

ack -r Client .

Find number of files where string `ToDo` occurs

ack -l 'ToDo' sourceDirectory | wc -l
  12

Find string `"FooBar"` in any `.*` files ignoring certain directories

$ pwd
/User/lumeng
$ ack --type=matlab --ignore-dir={subdir1,subdir2} "\"FooBar\""

Remarks:

/User/lumeng/subdir1, /User/lumeng/subdir2 are not searched;
--type=matlab specifies that files with file name extension .m is searched; Check ack --help=type for complete list of types;

Find `Plot` in Mathematica and related source code files

ack --type-add=wolfram:ext:.m,.nb,.cdf,.mt,.wl,.wlt --wolfram Plot

Optionally, add --type-add=wolfram:ext:.m,.nb,.cdf,.mt,.wl,.wlt to a ${HOME}/.ackrc and ue

ack --wolfram Plot
ack --nowolfram Plot

Examples of using grep

Tue, 16 May 2017 23:59:39 +0000

Find lines in `file1.txt` but not in `file2.txt`

grep -Fxvf file2.txt file1.txt

Find lines containing CJK characters from a file

grep --color=auto -P '.*\([^\x00-\x7f][^\x00-\x7f][^\x00-\x7f][^\x00-\x7f][^\x00-\x7f][^\x00-\x7f]\).* file.txt

Delete (really) empty lines

grep . oldfile > newfile

grep ^$ oldfile > newfile

or, delete really empty lines and lines with only whitespace characters

grep -E ^[[:whitespace:]]*$ oldfile > newfile

Change `};` to `}` in multiple files

grep -rl "};" *.m | xargs sed -i .bak -e 's/};/}/'

Remarks:

grep:

-r recursively find
-l list files matching text
xargs construct argument list and execute utility

sed:

-i .bak change in place but keep backup with extension .bak
-e execute command, in this case, a regex substitution

After programmatically munging a text file, detect unexpectedly changed lines that don't match certain pattern

If the expected changes will have string1 and string2 and the unexpected ones should not have them, use diff to find the changesets

$ diff file1.txt file2.txt > diff12.txt

and find the ones that don't have string1 and string2

    $grep -vE -e '(^.*string2|string2.*$)|^---$|^[[:digit:]]+(,[[:digit:]]+)*c[[:digit:]]+(,[[:digit:]]+)*$' diff12.txt

If you only want to count how many such lines there are, do -vEc instead of -vE.

Remarks:

-c: count but don't echo the matching lines
-v: boolean negate the test
-E: use POSIX extended regular expression
^---$|^[[:digit:]]+(,[[:digit:]]+)*c[[:digit:]]+(,[[:digit:]]+)*$ are used to match the lines "---" and "5918,5925c5918,5925" that diff generates for diff file1.txt file2.txt

Finding files that do not contain a given string

Find all files:

$ find . -type f -name "*.txt" > /tmp/all.txt

Find files that contain string foobar:

$ ack -l foobar > /tmp/positive.txt

Find the complement using grep:

$ grep -v -x -f /tmp/positive.txt /tmp/all.txt

Remarks:

-v invert the matching, selecting non-matching cases;
-x matches the entire line
-f <file name> takes patterns from file.

Extract parts related to the `-a` option from man page of `git`

git help commit 10 | grep -B 1 -A 10 "\-a" | more

pages tagged ack

Examples of using ack

Find instances of ToDo in source files

Find number of files where string ToDo occurs

Find string "FooBar" in any .* files ignoring certain directories

Find Plot in Mathematica and related source code files

Examples of using grep

Find lines in file1.txt but not in file2.txt

Find lines containing CJK characters from a file

Delete (really) empty lines

Change }; to } in multiple files

After programmatically munging a text file, detect unexpectedly changed lines that don't match certain pattern

Finding files that do not contain a given string

Extract parts related to the -a option from man page of git

Find instances of `ToDo` in source files

Find number of files where string `ToDo` occurs

Find string `"FooBar"` in any `.*` files ignoring certain directories

Find `Plot` in Mathematica and related source code files

Find lines in `file1.txt` but not in `file2.txt`

Change `};` to `}` in multiple files

Extract parts related to the `-a` option from man page of `git`