sorting - Merge files with sort -m and give error if files not pre-sorted? -

need out here.

i have 2 files,

    file1.txt >     5555555555     1111111111     7777777777      file2.txt >     0000000000     8888888888     2222222222     4444444444     3333333333 

when run, $ sort -m file1.txt file2.txt > file-c.txt output file-c.txt merged within file1 , file2 not sorted.

    file-c.txt >     0000000000     5555555555     1111111111     7777777777     8888888888     2222222222     4444444444     3333333333 

when happens need error saying files (file1 , file2) not sorted , merge can't merge files before has been sorted. when run $ sort -m file1.txt file2.txt > file-c.txt have error saying cannot merge file1 , file2 file-c because not yet sorted.

hope guys understand me :d

if understand you're asking, this:

diff1=$(diff <(cat file1.txt) <(sort file1.txt)) diff2=$(diff <(cat file2.txt) <(sort file2.txt)) if [ "$diff1" != "" ]; echo 'file1 not sorted' elif [ "$diff2" != "" ]; echo 'file2 not sorted' else sort -m file1.txt file2.txt fi 

this works in bash (and other shells) , following:

1. set diff1 variable output of diff of cat , sort of file1 (this empty if cat , sort same meaning if file sorted
2. set diff2 variable in same manner diff1 file2
3. do simple if .. elif .. else check , see whether file1 , file2 sorted, , if command line sort of two

is looking for?

edit: alternately per @twalberg if version of sort supports it, can this:

if ! sort -c file1.txt echo 'file1 not sorted' elif ! sort -c file2.txt echo 'file2 not sorted' else sort -m file1.txt file2.txt fi