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There are two command in Unix that allow to parse the fully qualified file name: dirname and basename. One extract path, the other file name.
Code:dirname "/home/one/two/three/myfile.txt"
Code:
echo "/home/one/two/three/myfile.txt" | sed 's|\(.*\)/.*|\1|'
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Bash script - how to get 'basename' command to do what I want..?(SOLVED)
Hi script guru's..Posted this earlier on the "Non-*NIX" section of this forum, but felt that I might get more response in this section instead - sorry for double posting..!!
I need some help with my script..(duh)..
I'm having trouble trying to work out how to use the "basename" command to perform what I want..
Here's the section of my script that needs review:
Code:
#--------------------------------- # Decoding #--------------------------------- else # if [ "$a" == "bfe" ] Xdialog --screen-center --wrap --no-buttons --title "INFO" --infobox "Decoding file.!" 160x50 2000 >&1 wait1 bcrypt $FILE < "$FIL2" 2>/dev/null if [ $? -eq 1 ];then error2 else Xdialog --screen-center --wrap --no-buttons --title "INFO" --infobox "Pass 1 completed.!" 180x50 2000 >&1 wait1 FILE=`basename "$FILE" .bfe` mv "$FILE" `basename "$FILE" .bfx`.bfe wait1 pkey1 wait1 bcrypt `basename "$FILE" .bfx`.bfe < "$input" 2>/dev/null if [ $? -eq 1 ];then erpkey bcrypt `basename "$FILE" .bfx`.bfe < "$input1" 2>/dev/null if [ $? -eq 1 ];then error3 else echo "OK" Xdialog --screen-center --wrap --no-buttons --title "INFO" --infobox "Decoding completed.!" 180x50 3000 >&1 rm -f $input rm -f $input1 exit 0 fi else rm -f $input Xdialog --screen-center --wrap --no-buttons --title "INFO" --infobox "Decoding completed.!" 180x50 3000 >&1 exit 0 fi fi fiThe 'wait1' 'error2' 'pkey1' 'erpkey' 'error3' 'opcanc' are internal functions which are defined at the top of the main script..Here is the 'error3' function that I would like to change :
Code:
function error3 { Xdialog --screen-center --title "ERROR" --msgbox "Still incorrect personal encryption key.\n\ Please ensure that the correct Personal key is used..\n\n\ Select OK to continue.." 400x160 if [ $? -eq 1 ];then opcanc else echo "OK" # need to add code to handle 're-encrypting' back to original file.. rm -f $input rm -f $input1 fi }----------------------------------------------------------------------------------
As whole of the script actually works very well - thanks to various friendly script guru's from other forums who helped with my niggling "bash scripting" questions..
----------------------------------------------------------------------------------Now where I would like to make the changes is in fact in the 'error3' code - but based on the section of the main script that calls it:
Code:
bcrypt `basename "$FILE" .bfx`.bfe < "$input" 2>/dev/null if [ $? -eq 1 ];then erpkey bcrypt `basename "$FILE" .bfx`.bfe < "$input1" 2>/dev/null if [ $? -eq 1 ];then error3 else echo "OK" fi
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Stack Overflow
The next script
str=/aaa/bbb/ccc.txt echo "str: $str" echo ${str##*/} == $(basename $str) echo ${str%/*} == $(dirname $str)produces:
str: /aaa/bbb/ccc.txt ccc.txt == ccc.txt /aaa/bbb == /aaa/bbbThe question is:
- In bash scripts, when is it recommended to use commands dirname and basename and when the variable substitutions and why?
Asking mainly because:
str="/aaa/bbb/ccc.txt" count=10000 s_cmdbase() { let i=0 while(( i++ < $count )) do a=$(basename $str) done } s_varbase() { let i=0 while(( i++ < $count )) do a=${str##*/} done } s_cmddir() { let i=0 while(( i++ < $count )) do a=$(dirname $str) done } s_vardir() { let i=0 while(( i++ < $count )) do a=${str%/*} done } time s_cmdbase echo command basename echo =================================== time s_varbase echo varsub basename echo =================================== time s_cmddir echo command dirname echo =================================== time s_vardir echo varsub dirnameon my system produces:
real 0m33.455s user 0m10.194s sys 0m18.106s command basename =================================== real 0m0.246s user 0m0.237s sys 0m0.007s varsub basename =================================== real 0m30.562s user 0m10.115s sys 0m17.764s command dirname =================================== real 0m0.237s user 0m0.226s sys 0m0.007s varsub dirnameCalling external programs (forking) costs time. The main point of the question is:
- Are there some pitfalls using variable substitutions instead of external commands?
I would say: dirname and basename are tools for very precise cases like this. Variable substitutions are for more general cases. So I would use dirname whenever I want the dir name, basename when I want the file name and variable substitutions whenever I need more general things that do not have a specific tool to get. – fedorqui Mar 14 '14 at 9:39
@fedorqui I would argue that dirname and basename are easier to read, especially for people who don't code shell on a daily basis (so that's a maintenance +1) but the performance difference is a fair point. I'd argue that as soon as you need them inside a loop (and not just on $0) you will want to consider using parameter substitution. – Adrian Frühwirth Mar 14 '14 at 10:11
===
The external commands make some logical corrections. Check the result of the next script:doit() { str=$1 echo -e "string $str" cmd=basename [[ "${str##*/}" == "$($cmd $str)" ]] && echo "$cmd same: ${str##*/}" || echo -e "$cmd different \${str##*/}\t>${str##*/}<\tvs command:\t>$($cmd $str)<" cmd=dirname [[ "${str%/*}" == "$($cmd $str)" ]] && echo "$cmd same: ${str%/*}" || echo -e "$cmd different \${str%/*}\t>${str%/*}<\tvs command:\t>$($cmd $str)<" echo } doit /aaa/bbb/ doit / doit /aaa doit aaa doit aaa/ doit aaa/xxxwith the result
string /aaa/bbb/ basename different ${str##*/} >< vs command: >bbb< dirname different ${str%/*} >/aaa/bbb< vs command: >/aaa< string / basename different ${str##*/} >< vs command: >/< dirname different ${str%/*} >< vs command: >/< string /aaa basename same: aaa dirname different ${str%/*} >< vs command: >/< string aaa basename same: aaa dirname different ${str%/*} >aaa< vs command: >.< string aaa/ basename different ${str##*/} >< vs command: >aaa< dirname different ${str%/*} >aaa< vs command: >.< string aaa/xxx basename same: xxx dirname same: aaaOne of most interesting results is the $(dirname "aaa"). The external command dirname correctly returns . but the variable expansion ${str%/*} returns the incorrect value aaa.
Alternative presentation
Script:
doit() { strings=( "[[$1]]" "[[$(basename "$1")]]" "[[${1##*/}]]" "[[$(dirname "$1")]]" "[[${1%/*}]]" ) printf "%-15s %-15s %-15s %-15s %-15s\n" "${strings[@]}" } printf "%-15s %-15s %-15s %-15s %-15s\n" \ 'file' 'basename $file' '${file##*/}' 'dirname $file' '${file%/*}' doit /aaa/bbb/ doit / doit /aaa doit aaa doit aaa/ doit aaa/xxx doit aaa//Output:
file basename $file ${file##*/} dirname $file ${file%/*} [[/aaa/bbb/]] [[bbb]] [[]] [[/aaa]] [[/aaa/bbb]] [[/]] [[/]] [[]] [[/]] [[]] [[/aaa]] [[aaa]] [[aaa]] [[/]] [[]] [[aaa]] [[aaa]] [[aaa]] [[.]] [[aaa]] [[aaa/]] [[aaa]] [[]] [[.]] [[aaa]] [[aaa/xxx]] [[xxx]] [[xxx]] [[aaa]] [[aaa]] [[aaa//]] [[aaa]] [[]] [[.]] [[aaa/]]
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Extract filename and extension in Bash >Oops! I didn't mean to do this. up vote744down votefavorite
398
I want to get the filename (without extension) and the extension separately. add a comment |The best solution I found so far is:
NAME=`echo "$FILE" | cut -d'.' -f1` EXTENSION=`echo "$FILE" | cut -d'.' -f2`This is wrong because it doesn't work if the file name contains multiple "." characters. If, let's say, I have a.b.js it will consider a and b.js, instead of a.b and js.
It can be easily done in Python with
file, ext = os.path.splitext(path)but I'd prefer not to fire a Python interpreter just for this, if possible.
Any better ideas?
This question explains this bash technique and several other related ones. – jjclarkson Jun 12 '09 at 20:34When applying the great answers below, do not simply paste in your variable like I show here Wrong:
extension="{$filename##*.}"like I did for a while! Move the$outside the curlys: Right:extension="${filename##*.}"– Chris K Aug 7 '13 at 18:5130 Answers 30
votes
up vote1501down voteaccepted First, get file without path: filename=$(basename "$fullfile") extension="${filename##*.}" filename="${filename%.*}"Alternatively, you can focus on the last '/' of the path instead of the '.' which should work even if you have unpredictable file extensions:
improve this answerfilename="${fullfile##*/}"edited Feb 11 '14 at 17:00 polymathcoder
6315answered Jun 8 '09 at 14:05 Petesh
39.7k33860Check out gnu.org/software/bash/manual/html_node/… for the full feature set. – D.Shawley Jun 8 '09 at 14:08
17 Add some quotes to "$fullfile", or you'll risk breaking the filename. – lhunath Jun 8 '09 at 14:34
30 Heck, you could even write filename="${fullfile##*/}" and avoid calling an extra basename– ephemient Jun 9 '09 at 17:52
13 This "solution" does not work if the file does not have an extension -- instead, the whole file name is output, which is quite bad considering that files without extensions are omnipresent. – nccc Jul 1 '12 at 3:42
62 I wish I could upvote each time I fall back on this answer because I can't remember. – Boris Guéry Jan 23
extract directory from file path
