unix - Appending multiple files into one file -


i append multiple data files single data file using cat command. how can assign single file value new file?

i using command:

cat file1 file2 file3 > newfile.txt anotherfile=`cat newfile.txt` sort $anotherfile | uniq -c

it showing error can not open anotherfile how assign newfile value file?

original answer original question

well, easiest way cp:

cat file1 file2 file3 > newfile.txt cp newfile.txt anotherfile.txt

failing that, can use:

cat file1 file2 file3 > newfile.txt anotherfile=$(cat newfile.txt) echo "$anotherfile" > anotherfile.txt

revised answer revised question

the original question had echo "$anotherfile" third line; revised question has sort $anotherfile | uniq -c third line.

assuming sort $anotherfile not sorting contents of files mentioned in list created concatenating original files (that is, assuming file1, file2 , file3 not contain lists of file names), objective sort , count lines found in source files.

the whole job can done in single command line:

cat file1 file2 file3 | tee newfile.txt | sort | uniq -c

or (more usually):

cat file1 file2 file3 | tee newfile.txt | sort | uniq -c | sort -n

which lists lines in increasing order of frequency.

if want sort contents of files listed in file1, file2, file3 list contents of each file once, then:

cat file1 file2 file3 | tee newfile.txt | sort -u | xargs sort | sort | uniq -c

it looks weird having 3 sort-related commands in row, there justification each step. sort -u ensures each file name listed once. xargs sort converts list of file names on standard input list of file names on sort command line. output of sorted data each batch of files xargs produces. if there few files xargs doesn't need run sort more once, following plain sort redundant. however, if xargs has run sort more once, final sort has deal fact first lines second batch produced xargs sort come before last lines produced first batch produced xargs sort.

this becomes judgement call based on knowledge of data in original files. if files small enough xargs won't need run multiple sort commands, omit final sort. heuristic "if sum of sizes of source files smaller maximum command line argument list, don't include sort".


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