combine two sed commands

Question

How can I combine the following two sed commands.

One loops all files in a directory and removes the first line from them. The other removes any double quotes " from the start of file lines.

Remove first line of each file

for each in `/bin/ls -1`;do sed -i 1d $each;done

Beginning of line

for each in `/bin/ls -1`;do sed -i 's/^"//g' $each;done

score 5 · Accepted Answer · answered Dec 02 '14 at 12:05

5

You can do:

for each in *; do sed -i.bak 's/^"//g; 1d' "$each"; done

answered Dec 02 '14 at 12:05

anubhava

761,203
64
569
643

2

Yeah, creating a backup file is a good practise. +1 for it. – fedorqui Dec 02 '14 at 12:10
1

I borrow you the `.bak` +1 – whoan Dec 02 '14 at 12:27

fedorqui · Answer 2 · 2014-12-02T13:04:45.867

You can use -e to perform different sed commands in the same line: sed -e 'command_1' -e 'command_2' ... -e 'command_n'. You can also use sed 'command_1; command_2; ...; command_n.

Let's use the first option and loop through the files:

for file in *
do
    sed -i.bak -e '1d' -e 's/^"//' "$file"
done

Note also that I use for file in *, so that * expands to the files in the current directory. This is better than parsing the output of ls (Why you shouldn't parse the output of ls(1) is a good read).

Finally, it is a good practise to create a backup file when using -i, as anubhava suggests. This way, you are always in the safe side :)

I was actually going to delete my answer since you answered first and with lot more details +1 — anubhava, Dec 02 '14 at 12:12

score 4 · Answer 3 · answered Dec 02 '14 at 12:07

4

You can put them into the same invocation of sed like this:

for f in *; do sed -i '1d;s/^"//' "$f"; done

As well as combining the two sed commands, I have also used a glob * rather than attempting to parse ls, which is never a good idea.

Also, your substitution needn't be global, as it can by definition only apply to each line once, so I removed the g modifier as well.

answered Dec 02 '14 at 12:07

Tom Fenech

72,334
12
107
141

A bit unfair that others answers have 3 upvotes while yours just 1. I already upvoted, but I would again as it is quite explanatory. – fedorqui Dec 02 '14 at 13:51
I guess that's the price I pay for writing the full answer in the first edit, rather than playing the game. Never mind! – Tom Fenech Dec 02 '14 at 13:52
For writing full explanation in first edit +1 – anubhava Dec 02 '14 at 14:31

score 4 · Answer 4 · edited Jun 20 '20 at 09:12

4

You can do it with a single commmand in this way:

sed -i.bak --separate '1d ; s/^"//' *

Explanation

With --separate you're telling sed to treat the files separately, the default is to process them as a long single file but you are using adresses (1 in the first command) so the default doesn't work.

'1d ; s/^"//' just combines the two commands (separated by ;).

edited Jun 20 '20 at 09:12

Community

1
1

answered Dec 02 '14 at 12:09

whoan

8,143
4
39
48

Didn't know about this gnu `--separate` option +1 – anubhava Dec 02 '14 at 12:24

combine two sed commands

4 Answers4

Explanation

Linked