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Here is a really straightforward example of using xargs to calculate a MD5 hash on every file in the current directory,
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ls | xargs -t -n1 md5 |
This is how it works,
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Thanks to the -t the output will be shown on screen,
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md5 planetary.doc
MD5 (bash) = ab5970d50d67bcafe5c554387f76534e
md5 Superman.jpg
MD5 (cat) = cdefa50d737dfcf8dc57886ea1a758c4
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Now let's get more advanced and use -I to allow substitution. First we'll create a some temporary files,
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mkdir temp
cd temp
touch files1 file2 file3 # Creates 3 empty files |
Now using xargs we will add the txt extension to each file,
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ls | xargs -t -I {} mv {} {}.txt
mv file1 file1.txt
mv file2 file2.txt
mv file3 file3.txt |
The -I {} specifies that the arguments by ls will be placed in the location of the {} called the replacement string. In fact you use whatever variable name you want instead of {}. For example, the following will also work,
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ls | xargs -t -I varX md5 varX
md5 file1.txt
MD5 (file1.txt) = d41d8cd98f00b204e9800998ecf8427e
md5 file2.txt
MD5 (file2.txt) = d41d8cd98f00b204e9800998ecf8427e
md5 file3.txt
MD5 (file3.txt) = d41d8cd98f00b204e9800998ecf8427e |
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The echo command is useful to test and see what xargs will be looping through,
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ls | xargs -I {} echo "mv {} {}.txt"
mv file1 file1.txt
mv file2 file2.txt
mv file3 file3.txt |
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Try to memorize this command,
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find [folder] -type f | xargs -I {} grep -li "text" {}
find [folder] -type f {search the specified folder for all files, returns full path of each file}
| xargs -I {} grep -li "[text]" {} {piped into xargs to grep for all files containing specified text ignoring case} |
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Try to memorize this command,
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find [folder] -type f | xargs -I {} grep -li "text" {} | xargs perl -pi -e 's/[text_to_search_for]/[text_to_search_for]/g'
find [folder] -type f # search the specified folder for all files, returns full path of each file
| xargs -I {} grep -li "[text]" {} # piped into xargs with to grep for all files containing specified text ignoring case}
| xargs perl -pi -e 's/[text_to_search_for]/[text_to_replace_with]/g' # pipe list of files and search/replace with specified text} |
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List directories from largest to smallest at the top level only.
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du -sk * | sort |
Long Running Processes
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Other Useful Commands
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digest -a md5 -v /path/to/file |