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| - | ====== shell tips ====== | ||
| - | Useful bash command for finding strings within python files... | ||
| - | |||
| - | <code bash> | ||
| - | find . -name \*.py -type f -print0 | xargs -0 grep -nI "timeit" | ||
| - | </code> | ||
| - | |||
| - | Interesting way to use ''grep -v'' to remove paths from a list generated by ''find''. Not sure about the escaped ''|'' character, though... | ||
| - | |||
| - | <code bash> | ||
| - | #!/bin/bash | ||
| - | find $PWD -regex ".*\.[hcHC]\(pp\|xx\)?" | \ | ||
| - | grep -v " \|unwantedpath/unwantedpath2\|unwantedpath3" > cscope.files | ||
| - | cscope -q -b | ||
| - | </code> | ||
| - | |||
| - | Here's how to find if a symbol is in a library, and how to search lots of object files and print the filename above the search... | ||
| - | |||
| - | <code bash> | ||
| - | nm obj-directory/libmyobject.a | c++filt | grep Initialize_my_obj | ||
| - | find bindirectory/ -name \*.a -exec nm /dev/null {} \; 2>/dev/null | \ | ||
| - | c++filt | grep -P "(^bindirectory.*\.a|T Initialize_my_obj)" | ||
| - | </code> | ||
| - | |||
| - | Also handy to merge two streams together... | ||
| - | |||
| - | <code bash> | ||
| - | ( cat file1 && cat file2 ) | sort | ||
| - | </code> | ||
| - | |||
| - | When a little quick math is needed, use ''bc'' | ||
| - | <code bash> | ||
| - | $ bc <<< "obase=16;ibase=10;15" | ||
| - | F | ||
| - | $ bc -l <<< 1/3 | ||
| - | .33333333333333333333 | ||
| - | $ bc <<< "scale=2; 1/3" | ||
| - | .33 | ||
| - | $ bc <<< "obase=10;ibase=16;B" | ||
| - | 11 | ||
| - | </code> | ||
| - | |||
| - | and, when coverting from hex to dec... | ||
| - | |||
| - | <code bash> | ||
| - | echo $((0x2dec)) | ||
| - | </code> | ||
| - | |||
| - | But, then again, does that really seem easier than, | ||
| - | |||
| - | <code> | ||
| - | python -c "print int('B',16)" | ||
| - | </code> | ||
| - | |||
| - | There's a bash way to calculate how many days ago a date was: | ||
| - | |||
| - | <code bash> | ||
| - | $ echo $(( ($(date +%s) - $(date -d "2012-4-16" +%s)) / 86400 )) | ||
| - | </code> | ||
| - | |||
| - | And a Python way... | ||
| - | |||
| - | <code python> | ||
| - | python -c "import datetime; print (datetime.date.today() - datetime.date( 2012, 4, 16 )).days" | ||
| - | </code> | ||
| - | |||
| - | And for displaying lines clipped at the right edge of the window instead wrapped: | ||
| - | |||
| - | <code bash> | ||
| - | cat_one_line_per_row() { | ||
| - | cat "$@" | expand | cut -b1-$COLUMNS | ||
| - | } | ||
| - | </code> | ||
| - | |||
| - | or a "clip" command like so: | ||
| - | |||
| - | <code bash> | ||
| - | alias clip="expand | cut -b1-\$COLUMNS" | ||
| - | </code> | ||
| - | |||
| - | ctags's man page says that one of its bugs is that it has too many options. Ain't that the truth. Make note of the obscure flag here, ''--c++-kinds=+p'', that tells ctags to process prototypes and method declarations. | ||
| - | |||
| - | <code bash> | ||
| - | ctags -n --if0=yes --c++-kinds=+p --langmap=c++:+.inl.lst \ | ||
| - | --langmap=asm:+.inc --file-tags=yes -R --extra=fq \ | ||
| - | --exclude=unwanted_file.lst \ | ||
| - | --exclude='*unwanted-directory*/*' \ | ||
| - | --regex-C++='/^.*CINIT.(.+),.*,.*,.*/CURLOPT_\1/' | ||
| - | </code> | ||
| - | |||
| - | When you want to repeat a command a few times... | ||
| - | <code bash> | ||
| - | seq 1 50 | xargs -I{} -n1 echo '{} Hello World!' | ||
| - | </code> | ||
| - | |||
| - | Keywords: bash shell sh zsh | ||
