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alex.blackbit
Advocate
Joined: 26 Jul 2005
Posts: 2397
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 Posted: Tue Nov 27, 2012 9:37 am Post subject: bash: detect last loop iteration [SOLVED] |
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Hi,
let's say I want to do something stupid like this: | Code: | #!/bin/bash
IFS='/'
FILE="/usr/bin/firefox"
for level in $FILE;
do
echo -n "${level}"
echo -n '/'
done
echo |
The output would be: | Code: | $ bash /tmp/script.sh
/usr/bin/firefox/
$ |
I want to get rid of the last slash.
My idea is to add an if statement to the loop to decide whether to output the slash or not, but I don't know what the condition would be.
Of course this is a constructed example.
Thanks in advance.
Last edited by alex.blackbit on Thu Nov 29, 2012 2:54 pm; edited 1 time in total |
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jormartr
Apprentice
Joined: 02 Jan 2008
Posts: 174
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| Posted: Tue Nov 27, 2012 10:31 am Post subject: Re: bash: detect last loop iteration |
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Something like this?
| Code: |
IFS='/'
FILE="/usr/bin/firefox"
for level in $FILE;
do
echo -n "${level}"
# if ... then SLASH=1 || SLASH=0
echo -n '/'
done
[ $SLASH -eq 1 ] && FILE="$(echo "FILE" | sed 's:/$::')"
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ppurka
Advocate
Joined: 26 Dec 2004
Posts: 3246
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| Posted: Tue Nov 27, 2012 11:11 am Post subject: |
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Switch the order of the two echo's (to chop off the first /)
| Code: | #!/bin/bash
IFS='/'
FILE="/usr/bin/firefox"
cnt=0
for level in $FILE;
do
cnt=$(( $cnt + 1 ))
if [ $cnt -eq 1 ]; then
continue
fi
echo -n '/'
echo -n "${level}"
done
echo |
Alternatively, use bash arrays: | Code: | #!/bin/bash
IFS='/'
FILE="/usr/bin/firefox"
FA=( $FILE )
max_1=$((${#FA[@]}-1))
for ((i=0; i<$max_1; i++)); do
echo -n "${FA[$i]}"
echo -n '/'
done
echo ${FA[$max_1]}
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emerge --quiet redefined | E17 vids: I, II | Now using e from git | e18, e19, and kde4 sucks :-/ |
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Akkara
Administrator
Joined: 28 Mar 2006
Posts: 6337
Location: &akkara
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| Posted: Tue Nov 27, 2012 11:28 am Post subject: |
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My favorite way of handling these "insert in between" kinds of problems, is to insert as a prefix, but arrange for the first prefix to be empty. Like this: | Code: | #!/bin/bash
IFS='/'
FILE="/usr/bin/firefox"
slash=""
for level in $FILE;
do
echo -n "${slash}${level}"
slash="/"
done
echo
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_________________
The reason there appears to be no god in the world, is because he's overwhelmed constantly pulling all those miracles that are needed to keep all the software we're using, mostly working. |
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ppurka
Advocate
Joined: 26 Dec 2004
Posts: 3246
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| Posted: Tue Nov 27, 2012 2:53 pm Post subject: |
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| Akkara wrote: | My favorite way of handling these "insert in between" kinds of problems, is to insert as a prefix, but arrange for the first prefix to be empty. Like this: | Code: | #!/bin/bash
IFS='/'
FILE="/usr/bin/firefox"
slash=""
for level in $FILE;
do
echo -n "${slash}${level}"
slash="/"
done
echo
|
|
Nice! I like this solution!
_________________
emerge --quiet redefined | E17 vids: I, II | Now using e from git | e18, e19, and kde4 sucks :-/ |
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alex.blackbit
Advocate
Joined: 26 Jul 2005
Posts: 2397
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| Posted: Thu Nov 29, 2012 2:53 pm Post subject: |
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Thanks for all the answers.
Akkaras solution is the most elegant I think, I'll use that. |
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Jimmy Jazz
Apprentice
Joined: 04 Oct 2004
Posts: 281
Location: Strasbourg
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| Posted: Thu Nov 29, 2012 11:40 pm Post subject: Re: bash: detect last loop iteration [SOLVED] |
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| alex.blackbit wrote: | Hi,
let's say I want to do something stupid like this: | Code: | #!/bin/bash
IFS='/'
FILE="/usr/bin/firefox"
for level in $FILE;
do
echo -n "${level}"
echo -n '/'
done
echo |
The output would be: | Code: | $ bash /tmp/script.sh
/usr/bin/firefox/
$ |
I want to get rid of the last slash.
My idea is to add an if statement to the loop to decide whether to output the slash or not, but I don't know what the condition would be.
Of course this is a constructed example.
Thanks in advance. |
For the last slash, you could write something like that,
| Code: |
#!/bin/bash
for pathname in /usr/bin/firefox/ /usr/bin/firefox; do
last=${pathname: -1}
case "$last" in
(/) echo is a slash
echo ${pathname::-1}
;;
(*) echo is something else
echo ${pathname}
;;
esac
done
$ ./fun
is a slash
/usr/bin/firefox
is something else
/usr/bin/firefox
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Also not supported by busybox ash
_________________
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